Method and device for reporting power headroom in mobile communication system for carrier aggregation

ABSTRACT

Provided are a method and apparatus for reporting power headroom in a mobile communication system supporting carrier aggregation. A user equipment (UE) determines the maximum transmit power for each carrier and the maximum UE transmit power, and sends a power headroom report that contains power headroom for each carrier computed based on the maximum transmit power for the carrier and the maximum UE transmit power to a corresponding base station (ENB).

PRIORITY

This application is the National Stage under 35 U.S.C. 371 ofInternational Patent Application No. PCT/KR2013/002224, filed on Mar.19, 2013, which claimed priority to U.S. Prov. App. Ser. No. 61/612,950filed on Mar. 19, 2012, U.S. Prov. App. Ser. No. 61/613,453 filed onMar. 20, 2012, U.S. Prov. App. Ser. No. 61/615,856 filed on Mar. 26,2012, and U.S. Prov. App. Ser. No. 61/620,957 filed on Apr. 5, 2012.

BACKGROUND

1. Field of the Disclosure

The present invention relates to a method and apparatus for reportingpower headroom in a mobile communication system supporting carrieraggregation and, more particularly, to a method that determines maximumtransmit power for each of multiple carriers and reports the determinedmaximum transmit power to a base station.

2. Description of the Related Art

In general, mobile communication systems have been developed to providecommunication services while guaranteeing user mobility. Thanks to rapidtechnological advancement, mobile communication systems are capable ofproviding not only voice communication services but also high-speed datacommunication services.

Recently, the 3rd Generation Partnership Project (3GPP) has been workingto standardize specifications for the Long Term Evolution (LTE) systemas a next generation mobile communication system. The LTE system aims torealize high-speed packet based communication supporting a data rate of100 Mbps exceeding existing data rates, and the specification thereof isnear completion.

After completion of the release 8 specification, various technologieshave been introduced to the LTE system to meet the ever increasingtraffic demand. Carrier aggregation (CA) is a representative technologyintroduced to the release 10 LTE specification.

In existing communication, a single carrier is used in between a userequipment (UE) and a base station (ENB). When carrier aggregation isemployed, a primary carrier and one or more secondary carriers may beused for communication between one UE and ENB, significantly increasingthe data transfer rate by an amount corresponding to the number ofsecondary carriers. In other words, it may be considered that one cellis formed by a downlink carrier and an uplink carrier provided by thesame ENB. In carrier aggregation, one UE may be considered as sendingand receiving data through multiple cells in parallel. In this case, themaximum data rate of the UE may be increased in proportion to the numberof aggregated carriers or cells.

In the LTE system, each carrier may be termed a component carrier (CC).A primary carrier may be termed a primary cell (PCell), and a secondarycarrier may be termed a secondary cell (SCell).

Frequency resources are limited. As different countries may usedifferent frequency resources or bands, it is not always possible toaggregate carriers belonging to the same frequency band only dependingon circumstances. To solve this problem, the release 11 LTEspecification provides enhanced carrier aggregation so that carriersbelonging to different frequency bands can be aggregated together.

The fact that a UE receives data through a downlink carrier andtransmits data through an uplink carrier may correspond in meaning to acase in which the UE sends and receives data using control and datachannels provided by a cell corresponding to the center frequencies andfrequency bands characterizing the carriers.

For the purpose of the description of the present invention, the termsused in general LTE system documents apply. For more details, TS 36.331and TS 36.321 (2011 December) may be referred to.

Meanwhile, for uplink scheduling, a UE reports various schedulinginformation (for example, buffer status report and power headroom (PH)report) to the corresponding ENB. The ENB may allocate a suitable amountof uplink transmission resources to the UE in consideration of thebuffer status and power headroom of the UE.

When carrier aggregation described above is employed, a UE may performuplink transmission at more than one serving cell. As uplinktransmission at multiple cells and uplink transmission at one cell mayhave different attributes, power headroom reporting (PHR) at a singlecell may not be directly applicable.

SUMMARY

Accordingly, an aspect of the present invention is to provide a methodand apparatus that enable, when a UE performs uplink transmission at oneor more serving cells, the corresponding ENB to identify accurate powerheadroom of the UE and minimize the frequency of power headroomreporting.

In accordance with an aspect of the present invention, a method ofreporting power headroom for a user equipment (UE) in a mobilecommunication system supporting multiple aggregated carriers isprovided. The method may include: receiving configuration informationfor multiple carriers to be aggregated and power headroom reporting froma base station (ENB); determining, upon reception of resource allocationfor uplink transmission to the ENB, the maximum transmit power for eachcarrier and the maximum UE transmit power; and sending a power headroomreport that contains power headroom for each carrier computed based onthe maximum transmit power for the carrier and the maximum UE transmitpower to the ENB.

In accordance with another aspect of the present invention, a method ofreceiving a power headroom report from a user equipment (UE) in a mobilecommunication system supporting multiple aggregated carriers isprovided. The method may include: sending configuration information formultiple carriers to be aggregated and power headroom reporting to theUE; sending resource allocation information for uplink transmission tothe UE; receiving a power headroom report that contains power headroomfor each carrier computed based on the maximum transmit power for thecarrier and the maximum UE transmit power from the UE; and performinguplink scheduling for the UE on the basis of the power headroom report.

In accordance with another aspect of the present invention, an apparatusfor reporting power headroom in a user equipment (UE) in a mobilecommunication system supporting multiple aggregated carriers isprovided. The apparatus may include: a transceiver unit to send andreceive signals to and from a base station (ENB) through multiplecarriers; and a control unit to control a process of receivingconfiguration information for multiple carriers to be aggregated andpower headroom reporting from the ENB, determining, upon reception ofresource allocation for uplink transmission to the ENB, the maximumtransmit power for each carrier and the maximum UE transmit power, andsending a power headroom report that contains power headroom for eachcarrier computed based on the maximum transmit power for the carrier andthe maximum UE transmit power to the ENB.

In accordance with another aspect of the present invention, an apparatusfor receiving a power headroom report from a user equipment (UE) in amobile communication system supporting multiple aggregated carriers isprovided. The apparatus may include: a transceiver unit to send andreceive signals to and from the UE through multiple carriers; and acontrol unit to perform a process of sending configuration informationfor multiple carriers to be aggregated and power headroom reporting tothe UE, sending resource allocation information for uplink transmissionto the UE, receiving a power headroom report that contains powerheadroom for each carrier computed based on the maximum transmit powerfor the carrier and the maximum UE transmit power from the UE, andperforming uplink scheduling for the UE on the basis of the powerheadroom report.

In a feature of the present invention, a data transmission and receptionapparatus and method using multiple carriers are provided. Even when aUE performs uplink transmission simultaneously at multiple servingcells, the corresponding ENB may perform scheduling in consideration ofpower headroom of the UE.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an LTE system architecture, to which the presentinvention is applied.

FIG. 2 illustrates a hierarchy of wireless protocols in the LTE system,to which the present invention is applied.

FIG. 3 depicts carrier aggregation.

FIG. 4 illustrates power headroom reporting (PHR).

FIG. 5 illustrates an extended PHR format.

FIG. 6 illustrates UE operation for PHR.

FIG. 7 illustrates a procedure for PWS message transmission andreception.

FIG. 8 illustrates UE operation for PWS message reception.

FIG. 9 illustrates another UE operation for PWS message reception.

FIG. 10 illustrates another UE operation for PWS message reception.

FIG. 11 illustrates frame timing of a non-synchronized new type cell.

FIG. 12 illustrates a procedure for obtaining the SFN of a new typecell.

FIG. 13 illustrates a procedure for obtaining the SFN performed by a UEbeing handed over to a new type cell.

FIG. 14 illustrates a procedure for measuring a new type cell.

FIG. 15 illustrates UE operation for determining the CRS pattern of anew type cell.

FIG. 16 illustrates UE operation for determining the measurement cycleof a new type cell.

FIG. 17 illustrates UE operation for activating and deactivating a newtype cell.

FIG. 18 illustrates a user equipment.

FIG. 19 illustrates a base station.

FIGS. 20 to 22 illustrate a configuration of a user equipment capable ofaggregating carriers belonging to distant frequency bands together forcarrier aggregation.

FIG. 23 illustrates a procedure for message exchange between a UE andENB in a first embodiment wherein maximum transmit powers of multiplepower amplifiers are distinct.

FIG. 24 illustrates UE operation in the first embodiment wherein maximumtransmit powers of multiple power amplifiers are distinct.

FIG. 25 illustrates a procedure for message exchange between a UE andENB in a second embodiment wherein maximum transmit powers of multiplepower amplifiers are distinct.

FIG. 26 illustrates UE operation in the second embodiment whereinmaximum transmit powers of multiple power amplifiers are distinct.

FIG. 27 illustrates a procedure for message exchange between a UE andENB in a third embodiment wherein maximum transmit powers of multiplepower amplifiers are distinct.

FIG. 28 illustrates UE operation in the third embodiment wherein maximumtransmit powers of multiple power amplifiers are distinct.

FIG. 29 illustrates a configuration of a UE according to an embodimentof the present invention.

FIG. 30 illustrates a configuration of an ENB according to an embodimentof the present invention.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present invention aredescribed as a solution to the above technical problem. Same names ofdefined entities may be used for ease of description of the presentinvention. Specific terms or words used in the description should beconstrued in accordance with the spirit of the present invention withoutlimiting the subject matter thereof, and may be applied to other systemshaving similar technical backgrounds without significant modification.

Next, embodiments of the present invention are described with referenceto the accompanying drawings.

FIG. 1 illustrates an LTE system architecture, to which the presentinvention is applied.

Referring to FIG. 1, the LTE radio access network is composed of basestations (Evolved Node Bs, ENBs) 105, 110, 115 and 120, a MobilityManagement Entity (MME) 125, and a Serving-Gateway (S-GW) 130. A userequipment (UE) 135 may connect to an external network through the ENBs105 to 120 and the S-GW 130.

The ENBs 105 to 120 may be connected to the UE 135 through wirelesschannels. The ENBs 105 to 120 correspond to Node Bs of the UMTS system,but perform more complex functions in comparison to existing Node Bs.

For example, in the LTE system, all user traffic including real-timeservices like VoIP (Voice over IP) services is served by sharedchannels.

Hence, it is necessary to perform scheduling on the basis of collectedstatus information regarding buffers, available transmit powers andchannels of UEs. Each of the ENBs 105 to 120 performs this schedulingfunction. To achieve a data rate of 100 Mbps in a 20 MHz bandwidth, theLTE system utilizes Orthogonal Frequency Division Multiplexing (OFDM) asradio access technology.

The UE 135 employs Adaptive Modulation and Coding (AMC) to determine themodulation scheme and channel coding rate according to channel states.

The S-GW 130 creates and removes data bearers for external networks andENBs 105 to 120 under control of the MME 125. The MME 125 is connectedto multiple ENBs and performs various control functions includingmobility management for UEs.

FIG. 2 illustrates a hierarchy of wireless protocols in the LTE system,to which the present invention is applied.

Referring to FIG. 2, in the LTE system, a UE and an ENB each include awireless protocol stack composed of a PDCP (Packet Data ConvergenceProtocol) layer 205 or 240, an RLC (Radio Link Control) layer 210 or235, a MAC (Medium Access Control) layer 215 or 230, and a physical(PHY) layer 220 or 225.

The PDCP layer 205 or 240 performs compression and decompression of IPheaders. The RLC layer 210 or 235 reconfigures PDCP PDUs (Protocol DataUnit) to a suitable size to conduct ARQ operations.

The MAC layer 215 or 230 forms connections between multiple RLC layerentities and PHY layer entities in a UE. The MAC layer 215 or 230multiplexes RLC PDUs into MAC PDUs and forwards the MAC PDUs to the PHYlayer 220 or 225. The MAC layer 215 or 230 demultiplexes MAC PDUs intoRLC PDUs and forwards the RLC PDUs to the RLC layer 210 or 235.

The PHY layer 220 or 225 converts higher layer data into OFDM symbols bymeans of channel coding and modulation and transmits the OFDM symbolsthrough a wireless channel. The PHY layer 220 or 225 converts OFDMsymbols received through a wireless channel into higher layer data bymeans of demodulation and channel decoding and forwards the data tohigher layers.

FIG. 3 illustrates a user equipment sending signals using carrieraggregation in a mobile communication system according to an embodimentof the present invention.

In FIG. 3, the ENB 305 transmits signals to the UE 330 and receivessignals from the UE 330 by use of multiple carriers across multiplefrequency bands.

For example, assume that the ENB 305 may use a carrier 315 with a centerfrequency f1 and a carrier 310 with a center frequency f3. In a normalsituation, the ENB 305 sends and receives signals to and from the UE 330through one of the two carriers 310 and 315. However, the UE 330 havinga carrier aggregation capability may use multiple carriers to send andreceive signals.

Hence, the ENB 305 may assign a number of carriers or serving cells tothe UE 330 having a carrier aggregation capability according to serviceconditions, increasing the data rate of the UE 330.

In the following description, “downlink” and “forward link” may be usedinterchangeably, and “uplink” and “reverse link” may be usedinterchangeably.

In the LTE system, the power headroom (PH) is related with the amount oftransmit power usable by the UE, and refers to the difference betweenthe maximum transmit power and the currently used transmit power of theUE. The power headroom may be defined with respect to the serving celland the UE. The power headroom for the serving cell may be defined bythe difference between the configured maximum UE transmit power forserving cell c P_(CMAX,c) and the UE transmit power currently used inthe serving cell. The power headroom for the UE (UE-specific powerheadroom) may be defined by the difference between the configuredmaximum UE transmit power P_(CMAX) and the overall UE transmit powercurrently used at a given point in time.

As scheduling is performed on a cell basis, uplink scheduling isaffected by the power headroom for the serving cell. In the currentspecification, the UE reports the power headroom only for the servingcell. However, in some cases, the UE-specific power headroom may be animportance factor for uplink scheduling.

As described above, the power headroom for the serving cell is thedifference between the configured maximum UE transmit power for servingcell c P_(CMAX,c) and the UE transmit power currently used in theserving cell, and may be expressed in Equations 1 to 3.P_(CMAX) _(_) _(L,c)≤P_(CMAX,c)≤P_(CMAX) _(_) _(H,c)  [Equation 1]P_(CMAX) _(_)_(L,c)=MIN{Pc_(EMAX,c)−T_(C,c),P_(PowerClass)−MAX(MPR_(c)+A-MPR_(IB,c),P-MPR_(c))−T_(C,c)}  [Equation2]P-CMAX_H,c=MIN{P_(Emax,c),P_(PowerClass)}  [Equation 3]

In Equation 1, P_(EMAX,c) is the maximum allowed UE transmit powersignaled by the eNB for serving cell c, and is sent to the UE throughsystem information SIB1. P_(PowerClass) is the maximum transmit powerdefined for each UE. P_(CMAX) _(_) _(L,c) is affected by variousparameters as shown in Equation 2.

In Equation 2, T_(C,c), MPR_(c), A-MPR_(c) and T_(IB,c) are parametersdefining limit values for adjusting the maximum UE transmit power in theserving cell to meet adjacent channel interference or spurious emissionrequirements, and are described in 3GPP TS 36.101. To be short, MPR_(c)is related to the amount of uplink transmission resources (i.e.bandwidth) and modulation scheme assigned to the UE. A-MPR_(c) isrelated to frequency bands, regional characteristics, and bandwidths foruplink transmission. A-MPR_(c) is used to cope with a frequency bandsensitive to adjacent spurious emission. T_(C,c) is used to allowadditional transmit power adjustment when uplink transmission is carriedout at the edge of a frequency band. T_(IB,c) is used to allowadditional transmit power adjustment when uplink transmission issimultaneously carried out in several serving cells with differentfrequency bands.

P-MPR_(c) is the maximum output power reduction applied to satisfy theSpecific Absorption Rate (SAR) requirement (limiting the amount of radiofrequency energy absorbed by the body to a preset level), and isdetermined according to the distance between the device and the body.For example, when a device is close to the body, a large P-MPR_(c) valueis applied to reduce the overall transmit power of the device. When adevice is far from the body, a small P-MPR_(c) value may be applied asthere is no need to reduce the overall transmit power of the device.

The UE may determine the maximum and minimum values for P_(CMAX,c) usingEquations 2 and 3 first, and select a value satisfying variousrequirements at a given point in time from between the two values.

In addition, the configured maximum UE transmit power P_(CMAX) may bedetermined according to Equations 4 to 6.

$\begin{matrix}{\mspace{76mu}{P_{{{CMAX\_ L}{\_ CA}}\;} \leq P_{CMAX} \leq P_{{CMAX\_ H}{\_ CA}}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack \\{P_{{{CMAX\_ L}{\_ CA}}\;} = {{MIN}\left\{ {{10\;\log_{10}{\sum{{MIN}\left\lbrack {\frac{P_{{EMAX},c}}{t_{C,c}},\frac{P_{PowerClass}}{\left( {{mpr}_{c},{a\text{-}{mpr}_{c}},t_{C,c},t_{{IB},c}} \right)},\frac{P_{PowerClass}}{{pmpr}_{c},t_{C,c}}} \right\rbrack}}},P_{PowerClass}} \right\}}} & \left\lbrack {{Equation}\mspace{14mu} 5} \right\rbrack \\{\mspace{79mu}{P_{{{CMAX\_ H}{\_ CA}}\;} = {{MIN}\left\{ {{10\;\log_{10}{\sum P_{{EMAX},c}}},P_{PowerClass}} \right\}}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

Here, mpr_(c), a-mpr_(c) and pmpr_(c) are the linear values of MPR_(c),A-MPR_(c) and P-MPR_(c), respectively.

As Equation 4 indicates, P_(CMAX) is autonomously selected by the UE andis not known to the ENB. Basically, the ENB performs uplink schedulingaccording to P_(CMAX,c) on a cell basis. When the overall UE transmitpower exceeds P_(CMAX) as a result of cell-basis uplink scheduling,uplink transmission performance may be degraded. To prevent this, it isnecessary for the UE to provide additional information to the ENB.

The relationship between P_(CMAX,c) and P_(CMAX) may be in one of thethree cases.

Case 1: P_(CMAX)=MIN{Σ^(log scale) P_(CMAX,c), P_(PowerClass)}

-   -   P_(CMAX) is equal to the sum of P_(CMAX,c) (or equal to the        maximum UE nominal transmit power P_(PowerClass)).

Case 2: P_(CMAX)>MIN{Σ^(log scale) P_(CMAX,c), P_(PowerClass)}

-   -   P_(CMAX) is greater than the sum of P_(CMAX,c).

Case 3: P_(CMAX)<MIN{Σ^(log scale) P_(CMAX,c), P_(PowerClass)}

-   -   P_(CMAX) is less than the sum of P_(CMAX,c).

For Case 1, the ENB may deduce P_(CMAX) from the sum of P_(CMAX,c). ForCase 2, P_(CMAX) does not affect scheduling. That is, the sum of uplinktransmit powers for cells does not exceed P_(CMAX). For Case 3, the sumof uplink transmit powers for cells may exceed P_(CMAX), in which casethe ENB needs to know UE P_(CMAX).

Hence, in the present invention, it is possible to enforce the UE toreport P_(CMAX) to the ENB only when the sum of uplink transmit powersfor cells exceeds the configured maximum UE transmit power (Case 3).

Meanwhile, the relationship between P_(CMAX,c) and P_(CMAX) may also bein one of the four cases.

Case 0: P_(CMAX)=P_(PowerClass)

-   -   P_(CMAX) is equal to P_(PowerClass)    -   the ENB may perform scheduling in consideration of P_(CMAX,c)        only.

Case 1′: P_(CMAX)=Σ^(log scale) P_(CMAX,c) & P_(CMAX)<P_(PowerClass)

-   -   P_(CMAX) is less than P_(PowerClass) and is equal to the sum of        P_(CMAX,c).    -   the ENB may perform scheduling in consideration of P_(CMAX,c)        only.

Case 2′: P_(CMAX)>Σ^(log scale) P_(CMAX,c) & P_(CMAX)<P_(PowerClass)

-   -   P_(CMAX) is greater than the sum of P_(CMAX,c) and is less than        P_(PowerClasss).    -   the ENB may perform scheduling in consideration of P_(CMAX,c)        only.

Case 3′: P_(CMAX)<Σ^(log scale) P_(CMAX,c) & P_(CMAX)<P_(PowerClass)

-   -   P_(CMAX) is less than the sum of P_(CMAX,c) and is less than        P_(PowerClass).    -   the sum of requested transmit powers may exceed P_(CMAX) if the        ENB performs scheduling in consideration of P_(CMAX,c) only.

Among the four cases, the UE may have to report P_(CMAX) to the ENB onlyin Case 3′.

FIG. 4 depicts overall UE and ENB operation according to theabove-described embodiment.

Referring to FIG. 4, in a mobile communication system including a UE 405and ENB 410, at step 415, the ENB configures carrier aggregation andpower headroom reporting (PHR) for the UE in consideration of UEcapabilities and network conditions. When multiple carriers or multipleserving cells are configured in the UE for the uplink, the ENB maydirect the UE to use the extended PHR functionality or extended PHR MACCE (control element).

For extended PHR configuration, the ENB may provide the UE with thefollowing PHR information (phr-Config).

-   -   periodicPHR-Timer: timer for periodic PHR. PHR is triggered upon        expiration of this timer.    -   prohibitPHR-Timer: timer for preventing too frequent PHR. New        PHR is not triggered while this timer is running.    -   dl-PathlossChange: when the downlink path loss has changed more        than dl-PathlossChange (dB), new PHR is triggered. Or, when        P-MPR change is greater than dl-PathlossChange new PHR is        triggered.    -   extendedPHR: indicates whether to use extended PHR.

Upon reception of such control message, the UE may perform uplink anddownlink configuration accordingly and perform subsequent operations.

At step 420, the ENB allocates transmission resources to the UE for newuplink transmission at a desired point in time. At step 425, the UEchecks whether a PHR condition is satisfied. The PHR condition is metwhen at least one of the following events occurs.

-   -   periodicPHR-Timer expires.    -   prohibitPHR-Timer is not running and the path loss has changed        more than dl-PathlossChange dB for at least one activated        serving cell which is used as a pathloss reference since the        last PHR transmission.    -   prohibitPHR-Timer is not running and the P_(CMAX) reporting        condition is satisfied. The P_(CMAX) reporting condition is        described later.

Upon satisfaction of the PHR condition, at step 430, the UE creates aPHR MAC CE. When PHR configuration indicates use of an extended PHR MACCE, the UE computes the PH for each serving cell using Equation 7 inconsideration of P_(CMAX,c) and requested transmit powers for activatedserving cells for uplink.PH(i)=P_(CMAX,c)(i)−{10 log₁₀(M_(PUSCH,c)(i))+P_(O) _(_)_(PUSCH,c)(i)+α_(c)(j)·PL_(c)+Δ_(TF,c)(i)±f_(c)(i)}  [Equation 7]

As Equation 7 indicates, PH(i) (power headroom at i^(th) subframe inserving cell c) is computed using P_(CMAX,c)(i) (configured maximum UEoutput power), M_(PUSCH,c)(i) (number of resource blocks), Δ_(TF,c)(power offset derived from the modulation coding scheme), PL_(c)(pathloss), and f_(c)(i) (accumulated TPC commands).

Here, PL_(c) is pathloss of a cell configured to provide pathloss to theserving cell c. The pathloss used to determine uplink transmit power ofa serving cell may be pathloss of a downlink channel of the serving cellor pathloss of a downlink channel of a different designated cell. Theserving cell to be used for pathloss reference may be selected by theENB and notified to the UE during call setup.

In addition, f_(c)(i) is the accumulated value of transmission powercontrol commands for the serving cell c. P_(O) _(_) _(PUSCH,c) is thesum of a cell-specific value and UE-specific value, and is determined bythe ENB and notified to the UE. α_(c) is a 3-bit cell-specific valuesupplied by the higher layers, is used as a weighting for pathloss inuplink transmit power computation (namely, a larger value implies thatthe pathloss has a stronger influence on uplink transmit power), and islimited according to the types of PUSCH transmission. Here, j indicatesthe type of scheduling used for PUSCH transmission. For example, j=0indicates PUSCH transmission using semi-persistently allocatedtransmission resources, j=1 indicates PUSCH transmission usingdynamically allocated transmission resources, and j=2 indicates PUSCHtransmission using transmission resources allocated during randomaccess.

For a serving cell without actual transmission, PH is computed by use ofP_(CMAX,c) determined by setting transmit power reduction to zero (0)and requested transmit powers determined by setting M_(PUSCH,c)(i) andΔ_(TF,c) to preset values (e.g. values corresponding respectively to thelowest MCS level and one transmission resource block). When transmitpower reduction is set to zero, P_(CMAX,c) and P_(CMAX) _(_) _(H,c) arethe same. Virtual PH reported by setting M_(PUSCH,c)(i) and Δ_(TF,c) topreset values in the absence of actual transmission may be meaningfullyutilized by the ENB for uplink scheduling on the serving cell in thenear future.

The format of PHR MAC CE is described later.

At step 435, the UE creates a MAC PDU and multiplexes the PHR MAC CEonto the MAC PDU. At step 440, the UE sends the MAC PDU to the ENB.

The UE maintains information on pathloss, P_(CMAX), P-MPR_(c) used forPH computation per serving cell and may use this information to checkPHR condition satisfaction in later uplink transmission.

Upon reception of the PHR MAC CE from the UE, at step 445, the ENBperforms uplink scheduling for the corresponding serving cell inconsideration of PH per serving cell and P_(CMAX,c). In addition, whenP_(CMAX) is contained in the PHR MAC CE, the ENB performs uplinkscheduling so that the sum of UE uplink transmit powers does not exceedP_(CMAX).

FIG. 5 illustrates the format of an extended PHR MAC CE.

To report power headroom for several serving cells in a mobilecommunication system with multiple aggregated carriers, it isadvantageous to send them in one PHR because of lower overhead. Unlikethe existing PHR MAC CE, the extended PHR MAC CE is designed to reportmultiple pieces of information such as PH and P_(CMAX,c) for severalcells. In FIG. 5, reference numerals 500 to 530 forms a bitmapindicating serving cells whose PH information is included in thisextended PHR MAC CE.

Each Ci bit corresponds to one SCell. Ci and SCell are related by SCellindex i. SCell index is notified by the ENB to the UE when SCell isassigned to the UE. The last bit 533 of the first byte is an unused(reserved) bit in the current specification, but may be used to indicatepresence of P_(CMAX) information in the present invention.

In a given byte, the P bit 535 indicates whether the configured maximumUE transmit power P_(CMAX) is affected by P-MPR_(c). As describedbefore, in the absence of actual PUSCH transmission at a serving cell,the UE may compute a PH value by use of a virtual transmission formatand assumed P_(CMAX,c). When a computed PH value is reported for aserving cell without actual uplink transmission, a given bit (V field540) of the corresponding byte is set to a preset value to indicate suchcomputed PH information. Here, the V field 540 is a 1-bit indicator usedfor this purpose.

The V field 540 may be set to a value (e.g. 0) when the PH value for acorresponding cell is computed based on real PUSCH transmission (usingan actual transmission format), and may be set to another value (e.g. 1)when the PH value to be reported is computed using a reference format(i.e. RB count=1, Δ_(TF)=0) and virtual P_(CMAX,c) because of no realPUSCH transmission at the corresponding cell.

The fields 545 and 555 may store PH and P_(CMAX,c) values. Both PH andP_(CMAX,c) values are reported for a serving cell with actual uplinktransmission, and only a PH value is reported for a serving cell withoutactual uplink transmission. Here, uplink transmission may refer to PUSCHtransmission and/or PUCCH transmission. The ENB collects and analyzesP_(CMAX,c) values for serving cells with actual uplink transmission, anduse the analysis result for uplink scheduling in the near future.

From the second byte in FIG. 5, a pair of PH and P_(CMAX,c) values (fora serving cell with real uplink transmission) or a P_(CMAX,c) value (fora serving cell without real uplink transmission) are stored in thefields 545, 555, 560, 565, 570 and 575 in a given order. Informationrelated to PCell is stored first, and values related to currently activeSCells are stored in ascending order of SCell index. For PCell, twotypes of PH values (Type 1 PH and Type 2 PH) may be stored. Type 1 PH isa value computed in consideration of PUSCH transmission only, and Type 2PH is a value computed in consideration of both PUSCH transmission andPUCCH transmission.

In addition, when the P_(CMAX) reporting condition is satisfied, the UEstores P_(CMAX) in the last byte 580 of the extended PHR MAC CE. LikeP_(CMAX,c), P_(CMAX) is represented by a 6-bit index indicating one ofpreset power levels.

As described above, whether P_(CMAX) is stored in the PHR MAC CE may beindicated by a given bit such as the field 533. Alternatively, whetherP_(CMAX) is stored may be implicitly indicated by the size of the PHRMAC CE. For example, assume that the bitmap and PH values have a size ofX bytes. Then, the size of the PHR MAC CE may be set to X+1 (bytes) whenP_(CMAX) is stored, and may be set to X (bytes) when P_(CMAX) (is notstored.

P_(CMAX) reporting conditions for the UE may include various conditionsillustrated below.

[P_(CMAX) Reporting Condition 1]

-   -   at least two different frequency bands are used by one or more        serving cells at which uplink transmission is performed,    -   P_(CMAX) is less than P_(PowerClass), and    -   the sum of P_(CMAX,c) for serving cells at which uplink        transmission is performed is greater than P_(CMAX) (i.e. in a        PHR MAC CE containing P_(CMAX), the sum of contained P_(CMAX,c)        values is greater than contained P_(CMAX)).

[P_(CMAX) Reporting Condition 2]

-   -   at least two different frequency bands are used by one or more        serving cells at which uplink transmission is performed,    -   P_(CMAX) is less than P_(PowerClass), and    -   when one P_(CMAX,c) value is selected for each of serving cells        at which uplink transmission is performed, the sum of the        selected P_(CMAX,c) values is greater than P_(CMAX). Here, for        each serving cell, the UE selects the P_(CMAX,c) value used to        compute Type 1 PH (e.g., when a first P_(CMAX,c) value        associated with Type 1 PH and a second P_(CMAX,c) value        associated with Type 2 PH are both reported for PCell, the UE        selects the first P_(CMAX,c) value associated with Type 1 PH).

[P_(CMAX) Reporting Condition 3]

-   -   at least two different frequency bands are used by one or more        serving cells at which uplink transmission is performed,    -   P_(CMAX) is less than P_(PowerClass), and    -   when one P_(CMAX,c) value is selected for each of serving cells        at which uplink transmission is performed, the sum of the        selected P_(CMAX,c) values is greater than P_(CMAX). Here, for        each serving cell, the UE selects the P_(CMAX,c) value related        to computation of the PH value based on the actual transmission        format (e.g., for PCell, when a first P_(CMAX,c) value        associated with Type 1 PH and a second P_(CMAX,c) value        associated with Type 2 PH are both reported and only PUCCH        transmission is performed, the UE selects the second P_(CMAX,c)        value associated with Type 2 PH).

FIG. 6 illustrates UE operation for PHR transmission to the ENB.

Referring to FIG. 6, at step 605, the UE receives a control messageindicating CA and extended PHR configuration and configures multipleserving cells and extended PHR according to the contents of the controlmessage. The control message contains control information such asphr-config and extendedPHR. Thereafter, the UE performs normaloperation.

At step 610, the UE receives allocation of transmission resources fornew uplink transmission. At step 615, the UE computes uplink transmitpower. Uplink transmit power is calculated for each serving cell.Specifically, for each serving cell, the UE determines P_(CMAX,c) byapplying Equations 1, 2 and 3, determines requested transmit power inconsideration of the number of transmission resource blocks,transmission format, pathloss, and the like, and selects the smaller oneof the two values as transmit power of the serving cell.

At step 620, the UE examines triggering of PHR. The UE may regardexpiration of prohibitPHR-Timer or satisfaction of the PHR reportingcondition as PHR trigger.

At step 625, the UE computes the PH value for each serving cell asindicated by Equation 4 in consideration of P_(CMAX,c) values ofcurrently active serving cells with uplink assignment and requestedtransmit powers. The UE stores the PH values for serving cells and otherinformation in an extended PHR MAC CE as illustrated in FIG. 5. At step630, if the P_(CMAX) reporting condition is satisfied, the UE adds thecurrent P_(CMAX) value to the extended PHR MAC CE.

At step 635, the UE adds the extended PHR MAC CE to a MAC PDU and sendsthe MAC PDU. Thereafter, the UE waits for allocation of new uplinktransmission resources.

Second Embodiment

When disasters such as an earthquake and tidal wave occur, this must bepromptly notified to the general public. Mobile communication systemssuch as LTE have a great advantage to delivery of Public Warning System(PWS) messages. For example, numerous persons carry mobile communicationterminals and it is possible to provide information to most mobilecommunication terminals in real time.

Security issues such as hacking have become increasingly serious andwidespread. As transmission of falsified PWS messages may cause seriousdisorder, it is necessary to deliver security information together withPWS messages so that integrity of the PWS messages may be verified.

FIG. 7 illustrates a procedure whereby the ENB delivers a PWS messagefrom a PWS server to the UE.

Referring to FIG. 7, to handle transmission of PWS messages, at step717, the UE 705 performs a security setting procedure with a PWS server715 to reach an agreement on security keys and algorithms in advance.

When an event requiring PWS message transmission occurs, at step 720,the PWS server 715 sends a PWS message to the ENBs 710. The PWS messagecontains both emergency description, evacuation measure and the like ascontents and security information. PWS is commonly known as ETWS(Earthquake Tsunami Warning System) or CMAS (Commercial Mobile AlertSystem). In the description, these terms may be used interchangeably.

At step 725, the ENB transmits the PWS message by use of a commoncontrol message such as system information so that all UEs remaining incells managed by the ENB can receive the PWS message.

Upon reception of the PWS message, at step 730, the UE checks integrityof the PWS message using security information contained in the message.That is, integrity checking is performed. If integrity checking issuccessful, at step 735, the UE delivers the PWS message to the user bydisplaying the PWS message on the screen. If integrity checking isunsuccessful, at step 745, the UE ignores and discards the PWS message.

On some occasions, a UE may be attached to a wireless network in limitedservice state. For example, when a network operator permitting access isnot present in a given region at a particular point in time, or when theUSIM is not installed, the UE may be attached to a wireless network inlimited service state during which only an emergency call is usable.When a UE is in limited service state, the UE may be unable to processsecurity information as the UE cannot receive imperatively necessaryinformation from the network operator. Hence, the UE in limited servicestate may be unable to deliver a PWS message containing securityinformation to the user.

It is reasonable to assume that only a small number of UEs are inlimited service state within one wireless network. Hence, although a UEin limited service state delivers a falsified PWS message to the user,this may be not a serious problem. On the other hand, when a UE inlimited service state does not deliver a PWS message to the user, avital problem may occur. As a result, it is undesirable for a UE failingto handle security information to unconditionally discard a PWS message.Rather, when a UE fails to process security information, it is desirableto check whether the cause is limited service state first, and todetermine whether to discard the PWS message or to deliver the PWSmessage to the user.

FIG. 8 illustrates UE operation in consideration of limited servicestate.

At step 805, the UE connects to a wireless network. The wireless networkmay be an LTE network or UMTS network. Connection to a wireless networkindicates identification of a wireless network sending receivable radiosignals and preparation of communication at a cell of the wirelessnetwork. In other words, the UE performs a registration procedure withthe wireless network and checks reception of a paging message through apaging channel of the wireless network. When a UE is connected to awireless network in limited service state, this indicates that the UEdoes not perform registration or has failed in registration.

The UE camps on a cell satisfying preset conditions (e.g. having commonchannel signal strength greater than or equal to a given threshold)among cells of the connected wireless network, and receives systeminformation to perform necessary operations in the cell. The systeminformation is broadcast in the form of System Information Block (SIB).In particular, SIB 1 is used to provide scheduling information forsystem information elements.

At step 810, the UE receives SIB 1. At step 815, the UE checks whetherPWS-related system information is scheduled. SIB 10, SIB 11 and SIB 12are examples of PWS-related system information. When PWS-related systeminformation is not present at the corresponding cell, this indicatesthat a PWS message is not sent at the current point in time, and the UEperforms regular operations until PWS-related system information isscheduled. When PWS-related system information is scheduled, at step820, the UE receives PWS-related system information at a given point intime according to the scheduling information.

At step 825, the UE examines an option for handling an unsecure PWSmessage. Examples of unsecure PWS messages includes a PWS message whosesecurity information is not verified, a PWS message having failed inintegrity test, and a PWS message having failed in security test.

To deal with an unsecure PWS message, an “unsecured PWS disable” fieldmay be provided in a stable storage (e.g. USIM) of the UE. When theunsecured PWS disable field is set to “Yes”, the UE does not process aPWS message having failed in security test; and when the unsecured PWSdisable field is set to “No”, the UE processes even a PWS message havingfailed in security test. Here, processing of a PWS message indicatesdisplaying or notifying the contents of the PWS message to the user.

If the unsecured PWS disable field is set to “No” at step 825, theprocedure proceeds to step 830. Otherwise, the procedure proceeds tostep 835.

At step 830, the UE performs necessary operations and displays contentsof the PWS message to the user. Here, the necessary operations mayinclude filtering of repeatedly received messages.

At step 835, the UE checks whether the PWS message is secure by applyingsecurity test to the security information of the PWS message. A securePWS message refers to a PWS message that is sent by a trusted device andis not falsified during transmission.

If the PWS message is a secure message, the procedure proceeds to step830. Otherwise (e.g. failure of or in security test such as integritytest), the procedure proceeds to step 840. At step 830, the UE performsnecessary operations and displays contents of the PWS message to theuser.

At step 840, the UE checks whether it is in limited service state. Whena UE is in limited service state, the UE can receive only a restrictedservice (for example, only emergency calls are allowed). If the USIM isnot inserted, if the UE is unable to find a suitable cell to camp on, orif the UE fails in registration, the UE enters limited service state. Asuitable cell is a cell conforming to the following conditions.

Namely, a suitable cell refers to a cell that belongs to a registeredPublic Land Mobile Network (registered PLMN), equivalent PLMN orselected PLMN, allows roaming thereto, and satisfies a cell selectioncriterion.

An equivalent PLMN, like the home PLMN, is a PLMN in which a UE mayregister to receive services. A UE may have multiple equivalent PLMNs. Alist of equivalent PLMNs may be signaled by the network to the UE or maybe stored in the memory. When the UE attempts to register in aparticular PLMN, the PLMN is referred to as a selected PLMN beforecompletion of registration.

Satisfaction of the cell selection criterion indicates that receivedsignal quality of the common channel is higher than or equal to a presetthreshold, and is detailed in 3GPP TS 36.304 (clause 5.2.3.2).

If in limited service state at step 840, the procedure proceeds to step830 at which the UE performs necessary operations and displays contentsof the PWS message to the user. If not in limited service state, theprocedure proceeds to step 845 at which the UE discards the received PWSmessage.

In FIG. 8, determination operations at steps 825, 835 and 840 may beperformed in a different sequence.

FIG. 9 illustrates another UE operation for PWS message reception.

It may be undesirable to apply a security procedure to all PWS messages.For example, application of a security procedure to PWS messages may beprohibited by national laws or regulations. To define a uniform formatfor PWS messages, it is possible to consider a scheme that insertssecurity information to all PWS messages and introduces an indicatorindicating whether to apply a security procedure to a particular PWSmessage. However, as security information may have a size ranging fromdozens scores of bytes to hundreds of bytes, it is desirable to avoidinsertion of security information if possible. In FIG. 9, securityinformation is treated as a selective field in the PWS message and UEoperation is described differently according to presence or absence ofsecurity information.

Steps 905, 910 and 915 of FIG. 9 are identical respectively to steps805, 810 and 815 of FIG. 8.

Referring to FIG. 9, at step 917, the UE checks whether the current PLMNis a PLMN designated for PWS message reception. The current PLMN may bea registered PLMN or selected PLMN. A field indicating a PLMN designatedfor PWS message reception may be present in a stable storage such as theUSIM in the UE. If the designated field is set to “Yes” and the currentPLMN is a home or equivalent PLMN, as the current PLMN is a PLMNdesignated for PWS message reception, the procedure proceeds to step920. If the designated field is set to “No” and the current PLMN is ahome or equivalent PLMN, as the current PLMN is not a PLMN designatedfor PWS message reception, the procedure proceeds to step 918.

At step 918, although PWS-related system information is present in thesystem information of the corresponding cell, the UE terminates the PWSreception procedure without reception of PWS-related system information.

At step 920, the UE receives PWS-related system information. SIB 10 andSIB 11 are examples of PWS-related system information. SIB 10 may beused to notify occurrence of an emergency situation, and may include anemergency type indicator (earthquake or tidal wave), and PWS messageidentifier and serial number. The UE may identify repeatedly receivedPWS messages using the message identifier and serial number.

SIB 11 may include a more detailed emergency description such as anevacuation direction or media clip on the emergency situation. In viewof importance, it is preferable to insert security information in SIB10. The UE may receive both SIB 10 and SIB 11 or receive SIB 10 first atstep 920, and proceed to step 923.

At step 923, the UE checks whether security information is contained inSIB 10. If security information is not contained, the procedure proceedsto step 930 at which the UE performs necessary operations and displayscontents of the PWS message to the user. If security information iscontained, the procedure proceeds to step 925 at which the UE checkswhether to apply a security procedure. In other words, when a PWSmessage not containing security information is received from a networkdesignated for PWS message reception, the UE processes the PWS messagefirst without consideration of the option for handling unsecure PWSmessages.

Steps 925, 930, 935, 940 and 945 of FIG. 9 are identical respectively tosteps 825, 830, 835, 840 and 845 of FIG. 8.

When new PWS information is posted or PWS information is changed, a UEcamping on a cell must promptly recognize this. When new PWS informationis posted or PWS information is changed, the ENB broadcasts a pagingmessage whose designated field is set to a preset value for a giventime. Upon reception of such a paging message, the UE initiates aprocedure to acquire PWS information.

FIG. 10 illustrates UE operation for receiving a paging message from theENB.

Step 1005 is identical to step 905 of FIG. 9.

Referring to FIG. 10, at step 1010, the UE receives a paging messagefrom the ENB. A paging message may be used to page a specific UE or toprovide common information such as modified system information tomultiple unspecified UEs. To notify PWS information modification to UEs,the ENB may broadcast a paging message containing a preset indication(hereinafter, referred to as “Indication 1”). The ENB repeatedlytransmits a paging message containing Indication 1 for a period of timelong enough to encompass paging times of all UEs within the cell,thereby permitting all UEs within the cell to recognizegeneration/modification of PWS messages.

Upon reception of a paging message, the UE checks whether Indication 1is contained in the paging message. Indication 1 is an indicator tomodification of PWS information. If Indication 1 is contained, theprocedure proceeds to step 1017. If Indication 1 is not contained, theprocedure proceeds to step 1016 at which the UE performs operationsaccording to the existing process.

At step 1017, the UE checks whether the current PLMN is a PLMNpermitting PWS message reception. A storage unit such as the USIM mayprovide two PLMN-related fields as follows.

-   -   field 1: indicates whether to receive a PWS message from the        home or equivalent PLMN or to ignore.    -   field 2: indicates whether to receive a PWS message from a        visited (or roamed) PLMN or to ignore.

The UE may determine whether to receive a PWS message from the currentPLMN on the basis of the field 1 and field 2 values. For example, whenthe current PLMN is a visited PLMN, if field 2 indicates “receive”, thecurrent PLMN is a PLMN permitting PWS message reception; and if field 2indicates “ignore”, the current PLMN is a PLMN not permitting PWSmessage reception.

If the current PLMN is a PLMN not permitting PWS message reception, theprocedure proceeds to step 1016 at which the UE performs operationsaccording to the existing process without initiating PWS messagereception. In most cases, PWS message reception is performed by a lowerlayer unit of the UE and PWS message processing is performed by a higherlayer unit according to PLMN types or settings. Hence, when the ENBtransmits a PWS message, a UE capable of PWS message reception receivesthe PWS message first and forwards the same to the higher layer unit.This causes a problem of receiving a PWS message that will not benotified to the user.

In the present invention, to address the above problem, PLMN types orsettings are examined in advance at the time of PWS message reception,so that a PWS message that will not be notified to the user is notreceived.

If the current PLMN is a PLMN permitting PWS message reception, theprocedure proceeds to step 1018 at which the UE receives SIB 1. The UEidentifies scheduling of PWS-related system information from SIB 1 andmonitors the downlink control channel for a given period of time todetect PWS-related SIBs.

At step 1020, the UE receives PWS-related SIBs. Step 1020 issubstantially identical to step 920 of FIG. 9.

Steps 1023, 1025 and 1030 of FIG. 10 are identical respectively to steps923, 925 and 930 of FIG. 9.

At step 1035, the UE checks whether the received PWS message is secure.If the PWS message has passed security test or integrity test, theprocedure proceeds to step 1030. If the PWS message containing securityinformation has failed in security test, as it is highly probable thatthe PWS message is a message sent by a malicious third party such as ahacker, the procedure proceeds to step 1040.

At step 1040, the UE discards the PWS message without presenting thesame to the user and logs the identifier and serial number of the PWSmessage. Later, when a PWS message whose identifier/serial number isidentical to a logged identifier/serial number is received, the PWSmessage is processed according to a normal process instead of beingfiltered as a duplicated message.

In other words, PWS messages that are discarded without being notifiedto the user because of failure in security test are treated differentlyfrom other PWS messages when duplicated. To be more specific, when a PWSmessage is received, the UE compares the identifier and serial number ofthe received PWS message with a stored log of identifiers and serialnumbers of previously received PWS messages to check duplication. If thereceived PWS message is a duplicated message, the UE checks whether thecorresponding previously received PWS message failed in security test.If the previously received PWS message did not failed in security test(success in security test passed or security test not performed), the UEdiscards the newly received PWS message on the ground of duplication. Ifthe previously received PWS message failed in security test, the newlyreceived PWS message is processed according to a normal process withoutbeing treated as a repeatedly received message.

Third Embodiment

Discussions are underway to introduce a new type of carrier to LTErelease 12. This is to increase spectrum efficiency by reducing inherentinefficiency of existing carriers, such as frequent transmission ofsystem information and Cell Reference Signals (CRS).

The new carrier does not provide system information. The UE may receivesystem information for the new carrier through a carrier associated withthe new carrier. For ease of description, a new type of carrier nottransmitting system information is referred to as a new carrier, and acarrier that is associated with a new carrier to provide necessaryinformation is referred to as a reference carrier. In the followingdescription, the words “carrier” and “cell” may be used interchangeably.

To provide system information for a new carrier by use of a commoncontrol signal or dedicated control signal of a reference carrier, ascheme that enables the reference carrier to provide the System FrameNumber (SFN) of the new carrier is needed.

In the LTE mobile communication system, the SFN is used as a criterionfor communication between the UE and ENB. Most operations aresuccessfully executed when the UE and ENB use the same SFN. For example,as the transmission time of a Sounding Reference Signal (SRS) is set onthe basis of the SFN, when the UE and ENB use different SFNs, SRStransmission and reception is not properly performed.

When time synchronization between the new carrier and reference carrieris established (i.e. radio frame boundaries of the two carriers orserving cells are coincide), a UE having achieved time synchronizationwith the reference carrier does not have to establish timesynchronization with the new carrier. For ease of description, the newcarrier time-synchronized with the reference carrier is referred to as asynchronized new carrier or a synchronized new type cell.

Although a synchronized new carrier is more efficient than anon-synchronized new carrier, it may be virtually impossible toestablish exact synchronization of a new carrier according to networkconditions. For ease of description, a new carrier not time-synchronizedwith an adjacent carrier is referred to as a non-synchronized newcarrier or a non-synchronized new type cell.

In the event that a UE accesses a synchronized new type cell, when theSFN of the synchronized new type cell is set to that of the referencecarrier cell (reference cell), no problem occurs as the UE and ENBassume the same SFN.

When a UE accesses a non-synchronized new carrier cell, a problem mayoccur as the radio frame of the non-synchronized new carrier cell doesnot coincide with that of the reference cell.

FIG. 11 illustrates a non-synchronized new carrier. Referring to FIG.11, the frame boundaries of the reference cell and non-synchronized newtype cell do not coincide and are misaligned by an amount indicated byreference numeral 1120. Here, the radio frame of the reference cellwhose SFN is x overlaps two radio frames 1125 and 1130 of thenon-synchronized new type cell. Hence, it is necessary to determinewhich of the two radio frames 1125 and 1130 will have SFN=x.

In the present invention, the ENB provides explicit information to theUE so that the SFN of a non-synchronized new type cell may be specified.

Explicit information provided by the ENB is 1 bit and may indicate oneof the two cases below.

-   -   0: the radio frame of the new type cell that does not precede        the radio frame with SFN=x of the reference cell and is nearest        thereto will have SFN=x (e.g. SFN of radio frame 1130 is x).    -   1: the radio frame of the new type cell that does not follow the        radio frame with SFN=x of the reference cell and is nearest        thereto will have SFN=x (e.g. SFN of radio frame 1125 is x).

When the amount of misalignment is very small, the ENB may not knowwhether the radio frames of the new serving cell will precede or followthe radio frames of the reference serving cell. In this case, the ENBmay not provide the above information and may designate the radio frameof the new type cell having the largest overlap with the radio framewith SFN=x of the reference cell to have SFN=x (e.g. SFN of radio frame1130 is x).

FIG. 12 illustrates an overall procedure for determining the SFN of anew type cell.

Referring to FIG. 12, at step 1225 the UE 1205 establishessynchronization with a cell 1210 of the ENB 1215 and specifies radioframes with SFN. The UE establishes synchronization with a cell throughcell search. Cell search and synchronization are described in 3GPP TS36.213 (section 4).

During synchronization, the UE receives a Primary Synchronization Signal(PSS) and a Secondary Synchronization Signal (SSS) from a cellexhibiting a channel quality level exceeding a preset threshold andrecognizes frame boundaries using the synchronization signals. The UEreceives system information from the cell and identifies the SFNspecifying radio frames by use of SFN information contained in theMaster Information Block (MIB) of the system information. The UE and ENBestablish RRC connections through a serving cell and perform uplink datatransmission and downlink data transmission.

At step 1230, the ENB determines to allocate a new serving cell to theUE or determines to hand over the UE. In particular, if the UE islocated in a region of a new type cell, the ENB may determine toallocate a new type cell to the UE or determine to hand over the UE to anew type cell.

At step 1235, the ENB sends a control message indicating serving celladdition or handover to the UE. The control message contains informationon a serving cell to be added (or to be the target for handover), suchas information related to the cell identifier, center frequency, radiotransmission resources. When the serving cell to be added (or to be thetarget for handover) is a new type cell, the following information maybe further included.

-   -   information for synchronization establishment    -   information for SFN acquisition    -   information on the reference cell

The above information may be delivered as follows according to the typeof the serving cell to be added (or to be the target for handover).

1. When the New Serving Cell is a Regular Cell

-   -   information for synchronization establishment, information for        SFN acquisition and reference cell information are all not        included.    -   when all the above three pieces of information are absent, the        UE recognizes that the serving cell to be added (or to be the        target for handover) and applies an existing procedure for        serving cell addition (or handover). For example, for handover,        the UE may establish synchronization with the new serving cell        and receive MIB of the new serving cell to specify frame        numbers.

2. When the New Serving Cell is a Synchronized New Type Cell

-   -   information for synchronization establishment and reference cell        information may be included.    -   the information for synchronization establishment indicates no        need for synchronization establishment.    -   the reference cell information indicates information on a        reference cell (such as cell identifier) that is used by the UE        to specify frame numbers of the new cell. In the case of        handover, the source cell becomes the reference cell by default.

3. When the New Serving Cell is a Non-Synchronized New Type Cell

-   -   information for synchronization establishment, information for        SFN acquisition and reference cell information may be included.    -   the information for synchronization establishment indicates a        need for synchronization establishment.    -   the information for SFN acquisition indicates one of “preceding”        and “following”.    -   the reference cell information indicates information on a        reference cell (such as cell identifier) that is used by the UE        to specify frame numbers of the new serving cell. In the case of        handover, the source cell becomes the reference cell by default.

At step 1240, the UE checks necessity of synchronization establishmenton the basis of the information for synchronization establishment in thecontrol message. If the information for synchronization establishmentindicates no need for synchronization establishment, the procedureproceeds to step 1245. If the information for synchronizationestablishment indicates a need for synchronization establishment, theprocedure proceeds to step 1247.

At step 1245, the UE does not attempt to receive the PSS/SSS of the newserving cell, applies the frame timing of the reference cell to the newserving cell without modification, and applies the SFN of the referencecell to the new serving cell without modification. Thereafter, theprocedure is ended.

At step 1247, the UE receives the PSS/SSS of the new serving cell toachieve frame synchronization. When frame synchronization with the newserving cell has been achieved before, step 1247 may be skipped.

At step 1250, the UE examines information for SFN acquisition. If theinformation for SFN acquisition is not included (i.e. synchronization isnecessary but SFN acquisition information is not included), theprocedure proceeds to step 1255. If the information for SFN acquisitionindicates “following”, the procedure proceeds to step 1260. If theinformation for SFN acquisition indicates “preceding”, the procedureproceeds to step 1265.

At step 1255, the UE specifies SFNs of radio frames of the new servingcell so that the SFN of a radio frame f of the new type cell is equal tothat of a radio frame of the reference cell having the largest overlapwith f on the time axis.

At step 1260, the UE specifies SFNs of radio frames of the new servingcell so that the SFN of a radio frame f of the new type cell is equal tothat of a radio frame of the reference cell following f and beingnearest to f.

At step 1265, the UE specifies SFNs of radio frames of the new servingcell so that the SFN of a radio frame f of the new type cell is equal tothat of a radio frame of the reference cell preceding f and beingnearest to f.

FIG. 13 illustrates a procedure for obtaining the SFN of a new type cellwhen the UE performs handover.

Referring to FIG. 13, at step 1305, the UE receives a control messageindicating handover from the ENB.

At step 1310, the UE checks whether first information (forsynchronization), second information (for SFN acquisition) and thirdinformation (on reference cell) are contained in the control message. Ifno such information is included (handover to regular serving cell), theprocedure proceeds to step 1315. If at least the first information isincluded (handover to new type cell), the procedure proceeds to step1320.

At step 1315, the UE establishes synchronization with the new cell,performs random access, receives MIB of the target cell, and recognizesSFNs of radio frames of the new cell.

At step 1320, the UE examines the first information to identifynecessity of synchronization with the new cell. If synchronization isnot needed (i.e. the new cell is a synchronized new type cell), theprocedure proceeds to step 1325. If synchronization is needed (i.e. thenew cell is a non-synchronized new type cell), the procedure proceeds tostep 1330.

At step 1325, the UE specifies frame timing by use of frame timing ofthe reference cell indicated by the third information, and recognizesSFNs of the new cell by use of SFNs of the reference cell. When thethird information is not present, the reference cell is the source cell(previous cell).

At step 1330, the UE examines the second information. If the secondinformation is not present, the procedure proceeds to step 1335. If thesecond information indicates “following”, the procedure proceeds to step1340. If the second information indicates “preceding”, the procedureproceeds to step 1345.

At step 1335, the UE receives the PSS/SSS of the new cell to achieveframe timing, and specifies SFNs of radio frames of the new cell so thatthe SFN of a radio frame f of the new cell is equal to that of a radioframe of the reference cell having the largest overlap with f on thetime axis.

At step 1340, the UE receives the PSS/SSS of the new cell to achieveframe timing, and specifies SFNs of radio frames of the new cell so thatthe SFN of a radio frame f of the new cell is equal to that of a radioframe of the reference cell following f and being nearest to f.

At step 1345, the UE receives the PSS/SSS of the new cell to achieveframe timing, and specifies SFNs of radio frames of the new cell so thatthe SFN of a radio frame f of the new cell is equal to that of a radioframe of the reference cell preceding f and being nearest to f.

To make a determination on handover or serving cell addition, the ENBhas to maintain information on channel states of the UE. To obtain suchinformation, the UE directs the UE to perform various measurements. RRMmeasurement is measurement performed for radio resource management.

Measurement of strength and quality of Cell Reference Signals (CRS) forthe current and neighbor cells is a representative example of RRMmeasurement. The UE reports measured signal strength/quality levels tothe ENB, which then makes RRM determinations on the basis of measurementreports.

CRS transmission is performed at each subframe in a regular cell. On theother hand, the frequency of CRS transmission is reduced to decreaseoverhead in a new type cell. For example, CRS transmission may beperformed once every five subframes in a new type cell. In the followingdescription, “CRS pattern” refers to a pattern of subframes at which CRStransmission is performed. As a single CRS pattern in which CRStransmission is performed at each subframe is present in a regular cell,it is not necessary to notify a CRS pattern when a measurement directionis issued for a regular cell.

However, as various CRS patterns may be present in a new type cell, itis necessary to provide CRS pattern information for each new type cell.The present invention provides a scheme that delivers CRS patterninformation to the UE when the ENB configures measurement objects in theUE.

FIG. 14 illustrates an overall procedure whereby the ENB provides CRSpattern information to the UE.

Referring to FIG. 14, at step 1415, the ENB 1410 determines to configureRRM measurement for the ENB 1405 at a suitable point in time. Forexample, a need to configure an additional serving cell or to directhandover occurs.

At step 1420, the ENB sends a measurement configuration messagecontaining measurement object information and the like to the UE.Measurement objects may be configured on a carrier basis, andmeasurement object information may include carrier frequency informationand SCell measurement cycle information (measCycleSCell). Here,measCycleSCell indicates a measurement cycle applied when SCell of thecorresponding carrier is deactivated to reduce UE battery consumption.

When a new type cell is present in the carrier to be measured, theflowing information may be further sent.

Information on the New Type Cell

-   -   CRS pattern information of the new type cell    -   PCI information of the new type cell    -   offset information to be applied to the new type cell    -   SCell measurement cycle information to be applied to the new        type cell

Here, CRS pattern information may be configured on a PCI (physical cellID, integer between 0 to 503) basis. A CRS pattern represents a form ofrepeated CRSs in a time-frequency grid. In a regular cell, CRSs aretransmitted over all frequencies of all subframes. For a cell whose CRSpattern is not explicitly specified, this default pattern is assumed.

In a new type cell, to reduce CRS overhead, CRS transmission isperformed only at selected frequencies of some subframes. CRS patterninformation indicates frequency resources of subframes through which CRStransmission is performed. CRS pattern information may include subframenumbers and frequency resource information, or include an index to oneof CRS patterns.

Examples of CRS pattern indexes are listed in Table 1.

TABLE 1 CRS Number of subframe Transmission pattern CRS transmission inwhich CRS is frequency index cycle (subframes) sent resource 0 1subframe (1 ms) all subframes all frequencies 1 2 subframes (5 ms) #0,#5 all frequencies 2 10 subframes (10 #1 6 PRBs (Physical ms) ResourceBlock) around center frequency . . . . . . . . . . . .

At the beginning of usage of new type cells, the number of CRS patternsmay be limited. When only one CRS pattern is defined, it may be possibleto know the CRS pattern to use by just indicating presence of a new typecell without separately specifying CRS pattern information.

In a carrier, regular cells and new type cells may coexist. In thiscase, PCIs of new type cells are explicitly indicated. When PCIs of newtype cells are consecutively allocated, information reduction may beachieved by specifying a range of PCIs. For example, a range of PCIs ofnew type cells may be specified by the first PCI and the number of PCIs.

When PCI information is not present in new type cell information, thisindicates that all cells of the corresponding carrier are a new typecell.

The UE measures a measurement object and compares a measured value witha preset reference value. Here, an offset may be added to or subtractedfrom the measured value to thereby adjust the measurement reportingcondition. In particular, when downlink transmit output of a new typecell is lower than that of a regular cell, a negative offset may beapplied, so that measurement results for the regular cell can becompared with those for the new type cell under comparable conditions.

It may be necessary for a new type cell to have a different SCellmeasurement cycle from a regular cell. This is because CRS transmissionis performed in all subframes of a regular cell while CRS transmissionis performed in some subframes of a new type cell. When a new type cellis included as a measurement object, a first SCell measurement cycle anda second SCell measurement cycle may be configured. The UE may apply thetwo SCell measurement cycles as follows.

-   -   when the first and second SCell measurement cycles are both        signaled, the UE applies the first SCell measurement cycle to a        regular cell and applies the second SCell measurement cycle to a        new type cell.    -   when only the first SCell measurement cycle is signaled (i.e.        the second SCell measurement cycle is not included in the new        type cell information), the UE applies the first SCell        measurement cycle to both a regular cell and a new type cell.        Or, the first SCell measurement cycle may be used as the second        SCell measurement cycle.

Upon reception of the measurement configuration message, at step 1425,the UE performs measurements on the measurement objects. Specifically,at step 1435, the UE applies a preset CRS pattern (e.g. Pattern 0) toperform measurements on a regular cell 1430. At step 1445, the UEapplies a signaled CRS pattern (e.g. Pattern 1) to perform measurementson a new type cell 1440.

Application of Pattern 1 indicates that CRS measurement is performedonly at a specific time/frequency of a subframe in which CRStransmission is performed through preset frequency resources asspecified by CRS pattern 1.

If the measurement result satisfies a preset reporting condition, atstep 1450, the UE sends a measurement report message to the ENB. At step1455, the ENB makes RRM-related determinations in consideration ofreported measurement results.

FIG. 15 illustrates UE operation in relation to a CRS pattern.

Referring to FIG. 15, at step 1505, the UE receives a control messagecontaining measurement object information from the ENB.

At step 1510, the UE checks satisfaction of a measurement initiationcondition for the measurement object. If the measurement initiationcondition is satisfied, the procedure proceeds to step 1515. Otherwise,the UE waits for satisfaction of the measurement initiation condition.Measurements on a measurement object are initiated only when a presetcondition is satisfied. For example, in the event that the measurementobject is not a serving carrier (or serving carrier), measurements maybe initiated only when channel quality of the serving cell becomes lowerthan a preset threshold.

At step 1555, the UE checks whether new type cell information iscontained in the measurement object information. Here, new type cellinformation indicates at least one of an indicator to presence of a newtype cell in the corresponding carrier, PCI information of the new typecell, and CRS pattern information of the new type cell.

If new type cell information is not contained, the procedure proceeds tostep 1520 at which the UE performs measurements on all cells specifiedas a measurement object (or on all PCIs of a carrier specified as ameasurement object) by use of a preset CRS pattern (e.g. CRS pattern#0).

If new type cell information is contained, the procedure proceeds tostep 1525 at which the UE checks whether new type cell PCI informationis contained. If new type cell PCI information is contained, theprocedure proceeds to step 1535. Otherwise, the procedure proceeds tostep 1530.

At step 1530, the UE determines that all cells (or all PCIs) of acarrier (or frequency) specified as a measurement object are a new typecell. The procedure proceeds to step 1540.

At step 1535, the UE determines that, among cells of a carrier specifiedas a measurement object, cells designated by PCI information are a newtype cell and the remaining cells are a regular cell. The procedureproceeds to step 1540.

At step 1540, the UE checks whether CRS pattern information iscontained. If CRS pattern information is contained, the procedureproceeds to step 1550. Otherwise, the procedure proceeds to step 1545.

At step 1545, the UE performs measurements on a regular cell by use of apreset CRS pattern (e.g. CRS pattern #0) and performs measurements on anew type cell by use of another preset CRS pattern (e.g. CRS pattern#1).

At step 1550, the UE performs measurements on a regular cell by use of apreset CRS pattern (e.g. CRS pattern #0) and performs measurements on anew type cell by use of an explicitly signaled CRS pattern.

Although CRS measurement is depicted in FIGS. 14 and 15, measurementsmay be performed using another reference signal such as Channel StateInformation-Reference Signal (CSI-RS). In this case, measurements on aregular cell may be performed using CRS pattern #0, and measurements ona new type cell may be performed using a preset CSI-RS pattern.Alternatively, measurements on a regular cell and measurements on a newtype cell may be performed using different CSI-RS patterns.

FIG. 16 illustrates UE operation for determining the measurement cycle.

Step 1605 and step 1610 of FIG. 16 are identical respectively to step1505 and step 1510 of FIG. 16.

At step 1615, the UE checks whether new type cell information iscontained in the measurement object information. Here, new type cellinformation indicates at least one of an indicator to presence of a newtype cell in the corresponding carrier, PCI information of the new typecell, and CRS pattern information of the new type cell.

If new type cell information is not contained, the procedure proceeds tostep 1620 at which the UE determines a measurement cycle according to anexisting scheme. If new type cell information is contained, theprocedure proceeds to step 1625.

At step 1625, the UE examines whether the carrier specified as ameasurement object is a serving frequency (in other words, a servingcell is configured in the carrier specified as a measurement object). Ifa serving frequency, the procedure proceeds to step 1630. If not aserving frequency, the procedure proceeds to step 1645.

At step 1630, the UE checks whether the serving cell configured in thecarrier specified as a measurement object is activated. If activated,the procedure proceeds to step 1640. If not activated, the procedureproceeds to step 1635.

SCell activation/deactivation is determined by a MAC layer controlmessage or a timer. The UE does not perform scheduling channel receptionor data reception for a deactivated serving cell, reducing batteryconsumption.

At step 1635, the UE determines the measurement cycle in considerationof the second SCell measurement cycle and DRX cycle. More specifically,the UE sets the measurement cycle to a longer one of the DRX cycle andsecond SCell measurement cycle. When only the first SCell measurementcycle is set or signaled while the second SCell measurement cycle is notsignaled, the UE may use the first SCell measurement cycle as the secondSCell measurement cycle. When neither the first SCell measurement cyclenor the second SCell measurement cycle is signaled, the UE may use theDRX cycle as the second SCell measurement cycle. When neither the firstSCell measurement cycle nor the second SCell measurement cycle issignaled and the DRX cycle is not set, the UE may use a preset timevalue (e.g. 40 ms) as the second SCell measurement cycle.

At step 1640, the UE determines the measurement cycle in considerationof the DRX cycle. For example, the measurement cycle is set to the DRXcycle. When the DRX cycle is not set, the measurement cycle is set to apreset time value (e.g. 40 ms).

At step 1645, the UE determines the measurement cycle in considerationof the number of frequencies to be measured (the number of non-servingfrequencies) excluding serving frequencies (frequencies at which PCellor SCell is configured). For example, the UE may set the measurementcycle to a time value obtained by multiplying the number of non-servingfrequencies and a preset value together. The UE may also set themeasurement cycle to a time value obtained by multiplying the number offrequencies containing a new type cell (among non-serving frequencies)and a preset value together.

FIG. 17 illustrates UE operation for adding a new type cell as a servingcell.

Referring to FIG. 17, at step 1705, the UE receives a control messageindicating addition of a new type serving cell. Here, the controlmessage may be an RRC connection reconfiguration message. Information ona serving cell to be added (such as information on the center frequencyand bandwidth of the serving cell to be added) is inserted in themessage.

When the new serving cell is a new type serving cell, this informationis also inserted. For example, a new type serving cell indication and areference serving cell ID may be further included in the message. Here,a reference serving cell refers to a serving cell providing framesynchronization and SFN to the new type cell. When a reference servingcell ID is not included, PCell is used as a reference serving cell.

At step 1710, the UE receives a downlink signal from the new servingcell, configures physical layer and MAC layer settings for uplink signaltransmission, and deactivates the new serving cell. The UE waits forreceiving MAC control information indicating activation of the newlyadded serving cell.

At step 1715, the UE receives an activation command. At step 1720, theUE activates the serving cell. When a serving cell is activated, a UEmay receive a downlink signal and send an uplink signal in the servingcell. The UE periodically sends channel quality information of theactivated serving cell to the ENB. The UE monitors a scheduling eventfor the activated serving cell.

At step 1725, the UE checks whether the activated serving cell satisfiesa deactivation condition while performing operations necessary for theactivated serving cell. Examples of deactivation conditions are asfollows.

-   -   reception of MAC control information indicating deactivation of        the serving cell;    -   expiration of a deactivation timer of the serving cell;    -   for a new type serving cell, reception of MAC control        information indicating deactivation of the reference serving        cell; or    -   for a new type serving cell, expiration of a deactivation timer        of the reference serving cell.

The deactivation timer is used to prevent a serving cell from being inactivated state for a long time, and is run for each serving cell. TheUE starts the deactivation timer when a corresponding serving cell isactivated, and restarts the deactivation timer when schedulinginformation (DL assignment or UL grant) for the serving cell isreceived. Expiration of the deactivation timer for a serving cellindicates that the serving cell has not been scheduled for a presettime, and causes the UE to deactivate the serving cell.

In the case of a new type serving cell, when the reference serving cellis deactivated, it becomes difficult to maintain frame timing. Hence,when the reference serving cell is deactivated, it is desirable todeactivate the new type serving cell as well.

FIG. 18 is a block diagram of a user equipment (UE) according to anembodiment of the present invention.

Referring to FIG. 18, the user equipment may include a transceiver unit1805, a control unit 1810, a mux/demux unit 1820, a control messagehandler 1835, various higher layer units 1825 and 1830, and a PWShandler 1837.

The transceiver unit 1805 receives data and control signals throughdownlink channels of a serving cell and sends data and control signalsthrough uplink channels. When multiple serving cells are configured, thetransceiver unit 1805 may send and receive data and control signalsthrough the multiple serving cells.

The mux/demux unit 1820 multiplexes data coming from the higher layerunits 1825 and 1830 or the control message handler 1835, anddemultiplexes data received by the transceiver unit 1805 and forwardsthe demultiplexed data to the higher layer units 1825 and 1830 or thecontrol message handler 1835.

The control message handler 1835 is an RRC layer entity that processes acontrol message received from a base station and performs acorresponding operation. For example, when RRC control messages arereceived, the control message handler 1835 forwards PHR information andnew type cell information to the control unit 1810 and forwardsPWS-related system information to the PWS handler 1837.

The higher layer units 1825 and 1830 may be configured on a servicebasis. The higher layer units 1825 and 1830 may process user datagenerated by service applications such as File Transfer Protocol (FTP)and Voice over Internet Protocol (VoIP) and forward the processed userdata to the mux/demux unit 1820, and delivers data coming from themux/demux unit 1820 to appropriate service applications at the higherlayer.

The control unit 1810 examines scheduling commands such as uplink grantsreceived through the transceiver unit 1805, and controls the transceiverunit 1805 and the mux/demux unit 1820 so that uplink transmissions areperformed at proper timings with appropriate transmission resources. Thecontrol unit 1810 manages overall procedures related to power headroomreporting, PWS message reception, and new type cell handling. Morespecifically, the control unit 1810 controls overall UE operationsdescribed in FIGS. 6 to 17.

The PWS handler 1837 may discard PWS-related system information ordeliver the same to the user interface under control of the control unit1810.

FIG. 19 is a block diagram of a base station (ENB) according to anembodiment of the present invention. Referring to FIG. 19, the basestation may include a transceiver unit 1905, a control unit 1910, amux/demux unit 1920, a control message handler 1935, various higherlayer units 1925 and 1930, a scheduler 1915, and a PWS handler 1937.

The transceiver unit 1905 sends data and control signals through adownlink carrier and receives data and control signals through an uplinkcarrier. When multiple carriers are configured, the transceiver unit1905 may send and receive data and control signals through the multiplecarriers.

The mux/demux unit 1920 multiplexes data coming from the higher layerunits 1925 and 1930 or the control message handler 1935, anddemultiplexes data received by the transceiver unit 1905 and forwardsthe demultiplexed data to the higher layer units 1925 and 1930, thecontrol message handler 1935 or the control unit 1910. The controlmessage handler 1935 processes a control message received from a UE andperforms a corresponding operation, and generates a control message tobe sent to a UE and forwards the control message to a lower layer.

The higher layer units 1925 and 1930 may be configured on a bearerbasis. The higher layer units 1925 and 1930 may compose RLC PDUs usingdata received from the S-GW or another ENB and forward the same to themux/demux unit 1920, and compose PDCP SDUs using RLC PDUs coming fromthe mux/demux unit 1920 and send the same to the S-GW or another ENB.

The scheduler 1915 allocates transmission resources to a UE atappropriate points in time in consideration of buffer states and channelstates, and controls the transceiver unit 1905 to send or receive asignal to or from the UE. The PWS handler 1937 performs operationsrelated to transmission of a PWS message from a PWS server.

The control unit 1910 manages overall procedures related to SCellconfiguration, RRC connection configuration, and handover. Morespecifically, the control unit 1910 controls overall ENB operations inrelation to UE operations described in FIGS. 6, 7, 11, 12, 13, 14, 15,16 and 17, and controls ENB operations described in FIG. 19.

The control unit 1910 manages overall procedures related to powerheadroom reporting, PWS message reception, and new type cell handling.More specifically, the control unit 1910 controls overall ENB operationsin relation to UE operations described in FIGS. 6 to 17, and controlsENB operations described in FIG. 19.

Next, another embodiment of the present invention is described. Thefollowing description is related to a power setting method and apparatusfor a user equipment having a transmitter structure composed of multiplepower amplifiers with different maximum transmit power values. Thepresent invention relates to a wireless communication system. Moreparticularly, the present invention relates to a transmit power settingmethod in a transmitter structure composed of multiple power amplifierswith different maximum transmit power values when carrier aggregation(CA) between carriers belonging to different frequency bands is employedin the Long Term Evolution (LTE) system.

FIGS. 20 to 22 illustrate examples of terminal structures supportingcarrier aggregation wherein non-contiguous carriers belonging todifferent frequency bands are aggregated.

As Type A of FIG. 20 indicates, as frequencies belonging to the sameband can be aggregated in carrier aggregation up to Release 10, onepower amplifier is sufficient for a UE. Hence, in the case of Type A,the maximum transmit power of a UE is equal to the maximum transmitpower of the power amplifier of the UE.

However, when data transmission is separately supported by differentbands as Type D1 of FIG. 21 and Type D2 of FIG. 22 indicate, signals areamplified by different power amplifiers (RF PA) for individual frequencybands. Hence, in the case of Type D1 or Type D2, the maximum transmitpower of a UE is no longer equal to the maximum transmit power of thepower amplifier of the UE. As this issue has not occurred up to Release10, it is necessary for the ENB to have accurate per-carrier informationof the UE for proper scheduling in the near future.

In a wireless communication system supporting carrier aggregationwherein carriers belonging to different frequency bands are aggregated,the UE may use separate power amplifiers to support transmission throughdifferent frequency bands. In such a case, the present inventionprovides a method that enables the ENB to know transmit powers of theindividual power amplifiers of the UE.

Specifically, to address the above problem, the present inventionproposes three embodiments as follows.

-   -   to send a Power Headroom Report (PHR), the UE sends a report for        each component carrier (CC) according to the value of a power        amplifier associated with the CC.    -   the difference between the maximum UE transmit power and the        current transmit power is reported in the original PHR. In the        present invention, the power headroom is computed using the        transmit power of each CC instead of the maximum UE transmit        power.    -   the UE explicitly notifies the ENB of actual maximum transmit        powers for each cell, frequency and frequency band, and the ENB        performs uplink scheduling using this information.    -   if overall UE transmit power exceeds the maximum transmit power,        transmit power adjustment is performed by scaling down the        transmit power according to ratios of transmit powers of        individual power amplifiers.

According to the above embodiments, even when the UE has multiple poweramplifiers with different maximum transmit powers, the UE may receivescheduling information from the ENB and send data in a manner conformingto the maximum transmit powers, enabling proper and efficient resourceutilization.

FIG. 23 illustrates a procedure for message exchange between a UE andENB in a first embodiment wherein maximum transmit powers of multiplepower amplifiers are distinct.

In FIG. 23, the UE 2301 is connected with the ENB 2309 supporting anumber of CCs. Upon connection of the UE 2301, at step 2311, the ENB2309 sends the UE 2301 a Radio Resource Control (RRC) message indicatingconfiguration of multiple CCs commensurate with UE capability.

For example, when the UE 2301 is CA-capable and supports frequency bandsmanaged by the ENB 2309, the ENB 2309 may configure the UE 2301 toutilize CA. For ease of description, it is assumed that SCell 1 (2305)and SCell 2 (2303) are additionally configured for the UE 2301, SCell 1and PCell (2307) are different frequencies belonging to the samefrequency band, and SCell 2 and PCell are distinct frequencies belongingto different frequency bands.

At step 2313, to activate the CCs configured in the UE 2301, the ENB2309 notifies the UE 2301 of SCell to be activated by sending anActivation/Deactivation MAC Control Element (CE) (MAC layer message). Inthe following description, it is assumed that both SCell 1 and SCell 2are indicated for activation. Upon reception of theActivation/Deactivation MAC CE, the UE 2301 activates the indicatedSCells.

Thereafter, the UE 2301 reports the difference between the maximum UEtransmit power and measured uplink transmit power for each activatedserving cell as a Power Headroom Report (PHR) to the ENB 2309 accordingto the existing conditions. For PHR transmission, the Power Headroom MACCE or Extended Power Headroom MAC CE may be used. The Extended PowerHeadroom MAC CE may be used to report the maximum transmit power foreach CC (P_(CMAX,c)) and the difference between the maximum transmitpower for each CC and measured uplink transmit power for the CC as aPower Headroom (PH) value.

At step 2321, the UE 2301 checks whether a PHR transmission condition issatisfied. As described before, conditions for PHR transmission aredescribed below. If at least one PHR transmission condition issatisfied, the UE 2301 creates a PHR at step 2323 and sends the PHR tothe ENB 2309 at step 2325.

-   -   prohibitPHR-Timer in the UE 2301 is not running and the path        loss has changed more than dl-PathlossChange dB for at least one        activated serving cell since the last PHR transmission    -   periodicPHR-Timer expires in the UE 2301    -   PHR configuration is changed by higher layer (RRC)    -   configured uplink is activated

Here, it is assumed that the UE 2301 supports inter-band noncontiguousCA wherein CCs belonging to multiple frequency bands are aggregated anduses power amplifiers having different maximum transmit powers to senddata through CCs belonging to different frequency bands. Hence, for PHreporting, the UE 2301 creates a PHR for each CC and the PH value iscomputed in consideration of the maximum transmit power of each poweramplifier at step 2323.

For example, for PH reporting in inter-band noncontiguous CA, themaximum UE transmit power for each CC (P_(CMAX,c)) is computed using themaximum UE transmit power. Table 2 illustrates equations defined in 3GPPTS 36.101 for computing the maximum UE transmit power for each CC(P_(CMAX,c)). In the case of inter-band noncontiguous CA being discussedin the present invention, it can be known that P_(CMAX,c) is computedusing the overall UE maximum transmit power (P_(PowerClass)).

TABLE 2 3GPP TS 36.101 . . . 6.2.5A Configured transmitted Power for CA. . . The configured maximum output power on serving cell c shall be setwithin the following bounds:  P_(CMAX)_L,c ≤ P_(CMAX,c) ≤ P_(CMAX)_H,cFor intra-band contiguous carrier aggregation: P_(CMAX)_L,c = MIN {P_(EMAX,c) − Δ_(TC,c), P_(PowerClass) − MAX(MPR _(c) + A-MPR _(c), P-MPR_(c) − ΔT_(C, c) } For inter-band non-contiguous carrier aggregation:P_(CMAX)_L,c = MIN { P_(Emax,c) − Δ_(TC,c), P_(PowerClass) − MAX(MPR_(c) + A-MPR _(c) + ΔT_(IB,c, P-MPR c) ) − ΔT_(C,c) } P_(CMAX)_H,c = MIN{P_(EMAX,c), P_(PowerClass)} P_(EMAX,c) is the value given by IE P-Maxfor serving cell c in [7]. P_(PowerClass) is the maximum UE powerspecified in TABLE 6.2.2-1 without taking into account the tolerancespecified in the TABLE 6.2.2-1. ΔT_(IB,c) is the additional tolerancefor serving cell c as specified in TABLE 6.2.5A-3 . . .

However, to compute the maximum UE transmit power for each CC for PHreporting, the present invention proposes utilizing the maximum transmitpower of a power amplifier corresponding to a frequency band to which aUE frequency belongs instead of utilizing the overall UE maximumtransmit power (P_(PowerClass)).

This point is described in more detail below. Referring to FIG. 23,assume that SCell 1 and SCell 2 belong to different frequency bands;uplink transmission on SCell 1 and uplink transmission on SCell 2 areperformed through power amplifiers with different transmitter structures(e.g. RF/PA #1 for uplink transmission on SCell 1, RF/PA #2 for uplinktransmission on SCell 2); and the maximum transmit power of PA #1 is 20dBm and the maximum transmit power of PA #2 is 23 dBm. To compute themaximum transmit power for SCell 1, the maximum transmit power of PA #1(20 dBm) is to be used instead of the P_(PowerClass) value; and tocompute the maximum transmit power for SCell 2, the maximum transmitpower of PA #2 (23 dBm) is to be used instead of the P_(PowerClass)value.

That is, in the above example, not the maximum transmit power of the UE2301 (e.g. 23 dBm) but the maximum transmit power of the serving cell(e.g. the maximum transmit power of a power amplifier mapped with theserving cell) is to be used as the P_(PowerClass) value.

When the P_(PowerClass) value is changed as described above, although atransmitter structure composed of multiple power amplifiers withdifferent maximum transmit powers is used, the maximum transmit power ofa power amplifier associated with the serving cell is reflected in theP_(CMAX,c) value reported by the UE through an extended PHR MAC CE.Hence, the UE may operate without malfunction.

At step 2325, the UE 2301 sends a PHR that contains P_(CMAX,c) and PHvalues reflecting the maximum transmit power of a power amplifierassociated with a CC. Upon reception of the PHR, at step 2327, the ENB2309 performs uplink scheduling for the UE 2301 on the basis of accurateinformation on the maximum transmit power of a power amplifiercorresponding to each CC and available power in the UE 2301. At step2331, the ENB 2309 receives data from the UE 2301.

FIG. 24 illustrates UE operation in the first embodiment wherein maximumtransmit powers of multiple power amplifiers are distinct.

Referring to FIG. 24, at step 2403, the UE attempts to access the ENBand is successfully connected with the ENB. Later, at step 2405, the UEreceives CA configuration information from the ENB and activatesconfigured CCs according to an activation command from the ENB.

At step 2407, the UE sends and receives data through the activated CCs.During data transmission and reception, at step 2409, the UE checkswhether a PHR transmission condition is satisfied. Conditions for PHRtransmission are described below. If at least one PHR transmissioncondition is satisfied, the UE has to perform PHR transmission.

-   -   prohibitPHR-Timer in the UE is not running and the path loss has        changed more than dl-PathlossChange dB for at least one        activated serving cell since the last PHR transmission    -   periodicPHR-Timer expires in the UE    -   PHR configuration is changed by higher layer (RRC)    -   configured uplink is activated

If at least one of the PHR transmission conditions is satisfied, at step2411, the UE checks whether multiple power amplifiers are used.Different values may be included in the PHR according to the number ofpower amplifiers.

If a single power amplifier is used, the procedure proceeds to step2413. At step 2413, for PHR transmission, the UE computes the maximum UEtransmit power for each CC (P_(CMAX,c)) using the maximum UE transmitpower (P_(PowerClass)). That is, when a single power amplifier is used,as the maximum transmit power for each CC is identical to the maximumtransmit power of the power amplifier, the maximum UE transmit power(P_(PowerClass)) is used without change to compute the values describedin FIG. 5.

If multiple power amplifiers are used (as discussed in the presentinvention), the procedure proceeds to step 2415. At step 2415, for PHRtransmission, the UE computes the maximum UE transmit power for each CCusing the maximum transmit power of a power amplifier associated withthe corresponding frequency band instead of using the overall maximum UEtransmit power (P_(PowerClass)).

At step 2417, the UE sends the PHR containing the values computed atstep 2413 or 2415 to the ENB. Thereafter, the procedure returns to step2407 for data transmission and reception.

FIG. 25 illustrates a procedure for message exchange between a UE andENB in a second embodiment wherein maximum transmit powers of multiplepower amplifiers are distinct.

In FIG. 25, the UE 2501 is connected to the ENB 2509 supporting multipleCCs.

In the event that the ENB 2509 or network has no information on thecapability of the UE 2501 after the UE 2501 is connected, at step 2511,the UE 2501 reports the effective maximum transmit power for each cell,frequency or frequency band to the ENB 2509.

As an example, for ease of description, it is assumed that the UE 2501uses two frequency bands; one frequency band is used for PCell (2507)and SCell 1 (2505) and another frequency band is used for SCell 2(2503); the UE 2501 has two power amplifiers (PA#1 for PCell and SCell1, PA#2 for SCell 2) with different maximum transmit powers; and themaximum transmit power P_(PowerClass) of PA#1 is 20 dBm and the maximumtransmit power P_(PowerClass) of PA#2 is 23 dBm.

In this case, the UE 2501 notifies the ENB 2509 at step 2511 that theeffective maximum transmit power for PCell and SCell 1 associated withPA#1 is 20 dBm and the effective maximum transmit power for SCell 2associated with PA#2 is 23 dBm. Here, the effective maximum transmitpower for each serving cell is signaled to the ENB 2509. However, theeffective maximum transmit power for each frequency or for eachfrequency band may also be signaled.

Thereafter, at step 2513, the ENB 2509 sends the UE 2501 an RRC layermessage indicating configuration of multiple CCs commensurate with UEcapability. For example, when the UE 2501 is CA-capable and supportsfrequency bands managed by the ENB 2509, the ENB 2509 may configure theUE 2501 to utilize CA.

At step 2515, to activate the CCs configured in the UE 2501, the ENB2509 notifies the UE 2501 of SCell to be activated by sending anActivation/Deactivation MAC CE (MAC layer message). In the followingdescription, it is assumed that both SCell 1 and SCell 2 are indicatedfor activation. Upon reception of the Activation/Deactivation MAC CE,the UE 2501 activates the indicated SCells.

At step 2521, the UE 2501 checks whether a PHR transmission condition issatisfied. Conditions for PHR transmission are described below. If atleast one PHR transmission condition is satisfied, the UE 2501 sends aPHR to the ENB 2509.

-   -   prohibitPHR-Timer in the UE 2501 is not running and the path        loss has changed more than dl-PathlossChange dB for at least one        activated serving cell since the last PHR transmission    -   periodicPHR-Timer expires in the UE 2501    -   PHR configuration is changed by higher layer (RRC)    -   configured uplink is activated

If at least one of the PHR transmission conditions is satisfied, at step2523, the UE 2501 sends a PHR to the ENB 2509. Upon reception of thePHR, at step 2525, the ENB 2509 performs uplink scheduling for the UE2501 by use of information on the effective maximum transmit power foreach cell, frequency or frequency band received at step 2511 andinformation in the PHR received at step 2523.

In other words, as described before, according to information on theeffective maximum transmit power for each cell received at step 2511 (avalue of 20 dBm as effective maximum transmit power P_(PowerClass) forSCell 1 (maximum transmit power of PA#1) and a value of 23 dBm aseffective maximum transmit power P_(PowerClass) for SCell 2 (maximumtransmit power of PA#2)), the ENB 2509 performs uplink transmissionscheduling on SCell 1 so that the requested uplink transmit power of theUE 2501 does not exceed 20 dBm, and performs uplink transmissionscheduling on SCell 2 so that the requested uplink transmit power of theUE 2501 does not exceed 23 dBm. In addition, as the overall maximumtransmit power of the UE 2501 is 23 dBm (larger one of 20 dBm and 23dBm), the ENB 2509 may perform uplink transmission scheduling so thatthe sum of requested transmit powers for uplink transmission on SCell 1and uplink transmission on SCell 2 does not exceed 23 dBm.

At step 2531, the ENB 2509 allocates resources to the UE 2501 accordingto the result of scheduling, and sends and receives data to and from theUE 2501.

FIG. 26 illustrates UE operation in the second embodiment whereinmaximum transmit powers of multiple power amplifiers are distinct.

Referring to FIG. 26, at step 2603, the UE attempts to access the ENBand is successfully connected with the ENB.

At step 2605, the UE checks whether multiple power amplifiers are used.If multiple power amplifiers are used, at step 2607, the UE reports theeffective maximum transmit power for each cell, frequency or frequencyband to the ENB. For ease of description, as depicted in FIG. 25, it isassumed that the UE uses two frequency bands; and one frequency band isused for PCell (2507) and SCell 1 (2505) and another frequency band isused for SCell 2 (2503).

It is further assumed that the UE has two power amplifiers (PA#1 forPCell and SCell 1, PA#2 for SCell 2) with different maximum transmitpowers; and the maximum transmit power P_(PowerClass) of PA#1 is 20 dBmand the maximum transmit power P_(PowerClass) of PA#2 is 23 dBm. In thiscase, the UE notifies the ENB at step 2607 that the effective maximumtransmit power for PCell and SCell 1 associated with PA#1 is 20 dBm andthe effective maximum transmit power for SCell 2 associated with PA#2 is23 dBm. Here, the effective maximum transmit power for each serving cellis signaled to the ENB. However, the effective maximum transmit powerfor each frequency or for each frequency band may also be signaled.

Thereafter, at step 2609, the UE receives CA configuration informationcommensurate with UE capability from the ENB and activates theconfigured CCs according to an activation command received from the ENB.

At step 2611, the UE sends and receives data through the activated CCs.During data transmission and reception, at step 2613, the UE checkswhether a PHR transmission condition is satisfied. Conditions for PHRtransmission are described below. If at least one of the PHRtransmission conditions is satisfied, the UE has to perform PHRtransmission.

-   -   prohibitPHR-Timer in the UE is not running and the path loss has        changed more than dl-PathlossChange dB for at least one        activated serving cell since the last PHR transmission    -   periodicPHR-Timer expires in the UE    -   PHR configuration is changed by higher layer (RRC)    -   configured uplink is activated

If at least one of the PHR transmission conditions is satisfied, at step2615, the UE sends a PHR to the ENB. Thereafter, the procedure returnsto step 2611 at which the UE may receive uplink scheduling from the ENBand send data through the activated CCs.

FIG. 27 illustrates a procedure for message exchange between a UE andENB in a third embodiment wherein maximum transmit powers of multiplepower amplifiers are distinct.

In FIG. 27, the UE 2701 is connected with the ENB 2709 supporting anumber of CCs. Upon connection of the UE 2701, at step 2711, the ENB2709 sends the UE 2701 an RRC layer message indicating configuration ofmultiple CCs commensurate with UE capability.

For example, when the UE 2701 is CA-capable and supports frequency bandsmanaged by the ENB 2709, the ENB 2709 may configure the UE 2701 toutilize CA. For ease of description, it is assumed that SCell 1 (2705)and SCell 2 (2703) are additionally configured for the UE 2701, SCell 1and PCell (2707) are different frequencies belonging to the samefrequency band, and SCell 2 and PCell are distinct frequencies belongingto different frequency bands.

At step 2713, to activate the CCs configured in the UE 2701, the ENB2709 notifies the UE 2701 of SCell to be activated by sending anActivation/Deactivation MAC CE (MAC layer message). In the followingdescription, it is assumed that both SCell 1 and SCell 2 are indicatedfor activation. Upon reception of the Activation/Deactivation MAC CE,the UE 2701 activates the indicated SCells.

Thereafter, the UE 2701 sends a PHR to the ENB 2709 according to presetPHR transmission conditions. At step 2721, the UE 2701 checks whether aPHR transmission condition is satisfied. Conditions for PHR transmissionare described below.

If at least one PHR transmission condition is satisfied, at step 2723,the UE 2701 sends a PHR to the ENB 2709.

-   -   prohibitPHR-Timer in the UE 2701 is not running and the path        loss has changed more than dl-PathlossChange dB for at least one        activated serving cell since the last PHR transmission    -   periodicPHR-Timer expires in the UE 2701    -   PHR configuration is changed by higher layer (RRC)    -   configured uplink is activated

Thereafter, at step 2731, the ENB 2709 performs uplink scheduling forthe UE 2701 in consideration of the received PHR and allocates resourcesto the UE 2701.

Upon reception of resource allocation, at step 2733, the UE 2701 checkswhether the sum of requested uplink transmit powers of frequenciesassociated with a power amplifier exceeds the maximum transmit power ofthe power amplifier on the basis of resource allocation information. Ifthe sum of requested uplink transmit powers of frequencies associatedwith a power amplifier exceeds the maximum transmit power of the poweramplifier, at step 2735, the UE 2701 scales down the requested uplinktransmit powers of the frequencies associated with the power amplifierso that the sum thereof does not exceed the maximum transmit power ofthe power amplifier. Scaling down may be performed using Equation 8below.Requested uplink transmit power of a frequency mapped with PA−(Sum ofrequested uplink transmit powers of frequencies mapped with PA−Maximumtransmit power of PA)/(Number of frequencies mapped with PA for uplinktransmission)  [Equation 8]

For example, assume that the maximum transmit power of the poweramplifier (PA#1) supporting PCell and SCell 1 is 20 dBm and the maximumtransmit power of the power amplifier (PA#2) supporting SCell 2 is 23dBm. When the sum of requested uplink transmit powers for PCell andSCell 1 (according to resource allocation by the ENB 2709) exceeds 20dBm of PA#1, the uplink transmit powers for PCell and SCell 1 are scaleddown so that the sum thereof does not exceed 20 dBm.

For PCell, the actual transmit power may be determined by Equation 9.Requested transmit power for PCell−(Requested transmit power for PCellRequested transmit power for SCell 1−20 dBm)/2  [Equation 9]

For SCell 1, the actual transmit power may be determined by Equation 10.Requested transmit power for SCell 1−(Requested transmit power for PCellRequested transmit power for SCell 1−20 dBm)/2  [Equation 10]

FIG. 28 illustrates UE operation in the third embodiment wherein maximumtransmit powers of multiple power amplifiers are distinct.

Referring to FIG. 28, at step 2803, the UE attempts to access the ENBand is successfully connected with the ENB. At step 2805, the UEreceives CA configuration information commensurate with UE capabilityfrom the ENB and activates configured CCs according to an activationcommand from the ENB.

Thereafter, at step 2807, the UE sends a PHR to the ENB and receivesresource allocation for uplink data transmission from the ENB.

At step 2809, for each CC, the UE checks whether the requested transmitpower of the CC indicated by resource allocation exceeds the P_(CMAX,c)value of the CC. If the requested transmit power of a CC exceeds theP_(CMAX,c) value of the CC, at step 2811, the UE scales down thetransmit power of the CC so that it does not exceed the P_(CMAX,c) valueof the CC. For example, the transmit power of a CC whose requestedtransmit power exceeds the corresponding P_(CMAX,c) value may be scaleddown to the P_(CMAX,c) value.

At step 2813, for each power amplifier, the UE checks whether the sum ofrequested transmit powers of frequencies mapped with the power amplifier(if scaled down at step 2811, scaled down values are used) exceeds themaximum transmit power of the power amplifier. If the sum of requestedtransmit powers of frequencies mapped with a power amplifier exceeds themaximum transmit power of the power amplifier, at step 2815, the UEscales down the uplink transmit powers of frequencies mapped with thepower amplifier so that the sum thereof does not exceed the maximumtransmit power of the power amplifier.

For example, assume that PCell, SCell 1 and SCell 2 are activated, andPCell and SCell 1 are mapped with PA#1 and SCell 2 is mapped with PA#2.When the sum of requested transmit powers of PCell and SCell 1 exceedsthe maximum transmit power of PA#1, the UE scales down the transmitpower of PCell using Equation 11 below.Requested transmit power for PCell−(Requested transmit power forPCell+Requested transmit power for SCell 1−Maximum transmit power ofPA#1)/2(Number of uplink frequencies mapped with PA#1)  [Equation 11]

The UE also scales down the transmit power of SCell 1 as above.

At step 2817, the UE checks whether the sum of requested transmit powersfor all frequencies (if scaled down at step 2811 or 2815, scaled downvalues are used) exceeds the maximum UE transmit power. If the sum ofrequested transmit powers for all frequencies exceeds the maximum UEtransmit power, at step 2819, the UE scales down the transmit powers forall frequencies so that the sum thereof does not exceed the maximum UEtransmit power.

For example, assume that PCell, SCell 1 and SCell 2 are activated, andPCell and SCell 1 are mapped with PA#1 and SCell 2 is mapped with PA#2.When the sum of requested transmit powers for PCell, SCell 1 and SCell 2exceed the maximum UE transmit power (here, the maximum UE transmitpower may be set to the larger one of the maximum transmit power of PA#1and the maximum transmit power of PA#2), the UE scales down the transmitpower of PCell using Equation 12 below.Requested transmit power for PCell−(Requested transmit power forPCell+Requested transmit power for SCell 1+Requested transmit power forSCell 2−Maximum UE transmit power)/3(Total number of uplinkfrequencies)  [Equation 12]

The UE scales down the transmit power of SCell 1 and SCell as above. Atstep 2821, the UE sends uplink data through allocated resources withtransmit powers adjusted as described above if necessary.

In FIG. 28, transmit power adjustment is performed with respect to themaximum transmit power for each CC, for each power amplifier, and for UEin sequence. However, the adjustment sequence may be changed. Forexample, transmit power adjustment may be performed with respect to themaximum transmit power for each CC, for UE, and for each power amplifierin sequence.

FIG. 29 illustrates a configuration of a user equipment according to thepresent invention.

Referring to FIG. 29, in the UE, the higher layer unit 2905 is used fortransmission and reception of data, and the control message handler 2907is used for transmission and reception of control messages.

For transmission, under control of the control unit 2909, data andmessages are multiplexed through the mux/demux unit 2903 and themultiplexed data is sent through the transceiver unit 2901. Forreception, under control of the control unit 2909, physical layersignals are received through the transceiver unit 2901, the receivedsignals are demultiplexed through the mux/demux unit 2903, and thedemultiplexed signals are forwarded to the higher layer unit 2905 or thecontrol message handler 2907 according to their types.

FIG. 30 illustrates a configuration of an ENB according to the presentinvention.

Referring to FIG. 30, in the ENB, the higher layer unit 3005 is used fortransmission and reception of data, and the control message handler 3007is used for transmission and reception of control messages.

For transmission, under control of the control unit 3009, data andmessages are multiplexed through the mux/demux unit 3003 and themultiplexed data is sent through the transceiver unit 3001. Forreception, under control of the control unit 3009, physical layersignals are received through the transceiver unit 3001, the receivedsignals are demultiplexed through the mux/demux unit 3003, and thedemultiplexed signals are forwarded to the higher layer unit 3005 or thecontrol message handler 3007 according to their types.

The method described above enables a user equipment having multiplepower amplifiers with different maximum transmit powers to receiveresource scheduling from the base station and send data thereto inaccordance with the different maximum transmit powers, making itpossible to utilize transmission resources in an accurate and efficientmanner.

The above description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the present invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of the presentinvention.

Hereinabove, embodiments of the present invention have been describedwith reference to the accompanying drawings. Specific terms or wordsused in the description should be construed in accordance with thespirit of the present invention without limiting the subject matterthereof. It should be understood that many variations and modificationsof the basic inventive concept described herein will still fall withinthe spirit and scope of the present invention as defined in the appendedclaims and their equivalents.

The invention claimed is:
 1. A method of performed by a terminaloperation in a wireless communication system, the method comprising:receiving a measurement configuration message from a first base stationcontrolling a first cell using a first frequency band; measuring a firstreference signal of the first cell from the first base station;measuring a second reference signal of a second cell using a secondfrequency band from a second base station based on the measurementconfiguration message; and transmitting a measurement report comprisingincluding a measurement result of the first reference signal and ameasurement result of the second reference signal to the first basestation, wherein the measurement configuration message includes patternfirst information comprising an indication of on which subframes thesecond reference signal is to be transmitted in, second information on aphysical cell identity of the second cell, and offset third informationon an offset for the second reference signal, and wherein the firstreference signal is transmitted in all subframes, and the secondreference signal is transmitted in subframes identified based on thepattern first information included in the measurement configurationmessage.
 2. The method of claim 1, wherein the first reference signal isa cell reference signal (CRS), and the second reference signal is achannel state indication reference signal (CSI-RS).
 3. A method ofoperation of performed by a first base station in a wirelesscommunication system, the method comprising: transmitting a measurementconfiguration message to a terminal; transmitting a first referencesignal of a first cell which is controlled by the first base station ona first frequency band to the terminal; and receiving a measurementreport from the terminal, wherein the measurement configuration messageincludes pattern first information for a second reference signal of asecond cell which is transmitted from a second base station using asecond frequency band, second information on a physical cell identity ofthe second cell, and offset third information on an offset for thesecond reference signal, wherein the pattern first information comprisesan indication of indicates which subframes the second reference signalis to be transmitted in;, wherein the measurement report comprisesincludes a measurement result of the first reference signal and ameasurement result of the second reference signal, and wherein the firstreference signal is transmitted in all subframes, and the secondreference signal is transmitted in subframes identified based on thepattern first information included in the measurement configurationmessage.
 4. The method of claim 3, wherein the first reference signal isa cell reference signal (CRS), and the second reference signal is achannel state indication reference signal (CSI-RS).
 5. A terminal in awireless communication system, the terminal comprising: a transceiverconfigured to transmit and receive signals; and a controller coupledwith the transceiver and configured to control to: control thetransceiver to receive a measurement configuration message from a firstbase station controlling a first cell using a first frequency band,measure a first reference signal of the first cell from the first basestation, measure a second reference signal of a second cell using asecond frequency band from a second base station based on themeasurement configuration message, and control the transceiver totransmit a measurement report comprisingincluding a measurement resultof the first reference signal and measurement result of the secondreference signal to the first base station, wherein the measurementconfiguration message includes pattern first information comprising anindication of on which subframes the second reference signal is to betransmitted in, second information on a physical cell identity of thesecond cell, and third information on an offset information for thesecond reference signal, and wherein the first reference signal istransmitted in all subframes, and the second reference signal istransmitted in subframes identified based on the pattern firstinformation included in the measurement configuration message.
 6. Theterminal of claim 5, wherein the first reference signal is a cellreference signal (CRS), and the second reference signal is a channelstate indication reference signal (CSI-RS).
 7. A first base station in awireless communication system, the first base station comprising: atransceiver configured to transmit and receive signals; and a controllercoupled with the transceiver and configured to control to: control thetransceiver to transmit a measurement configuration message to aterminal, control the transceiver to transmit a first reference signalof a first cell which is controlled by athe first base station on afirst frequency band to the terminal, and control the transceiver toreceive a measurement report from the terminal, wherein the measurementconfiguration message includes pattern first information for a secondreference signal of a second cell which is transmitted from a secondbase station using a second frequency band, second information on aphysical cell identity of the second cell, and third information on anoffset information for the second reference signal, wherein the patternfirst information comprises an indication of indicates which subframesthe second reference signal is to be transmitted in;, wherein themeasurement report comprises includes a measurement result of the firstreference signal and a measurement result of the second referencesignal, and wherein the first reference signal is transmitted in allsubframes, and the second reference signal is transmitted in subframesidentified based on pattern the first information included in themeasurement configuration message.
 8. The first base station of claim 7,wherein the first reference signal is a cell reference signal (CRS), andthe second reference signal is a channel state indication referencesignal (CSI-RS).